feat: add call ringing API (#6650)

this PR adds a "ringing" api that can be used for calls later.

see deltachat.h for details about the API; jsonrpc is left out until
things are settled for the needs of android/iOS

UI using this PR already successfully are
https://github.com/deltachat/deltachat-ios/pull/2638 and
https://github.com/deltachat/deltachat-android/pull/3785 ; the "payload"
passed forth and back is optimised for
https://github.com/deltachat/calls-webapp

---------

Co-authored-by: l <link2xt@testrun.org>

deltachat-ffi/deltachat.h

@@ -1215,6 +1215,103 @@ void             dc_set_webxdc_integration (dc_context_t* context, const char* f
 uint32_t        dc_init_webxdc_integration    (dc_context_t* context, uint32_t chat_id);
 
 
+/**
+ * Start an outgoing call.
+ * This sends a message with all relevant information to the callee,
+ * who will get informed by an #DC_EVENT_INCOMING_CALL event and rings.
+ *
+ * Possible actions during ringing:
+ *
+ * - caller cancels the call using dc_end_call():
+ *   callee receives #DC_EVENT_CALL_ENDED
+ *
+ * - callee accepts using dc_accept_incoming_call():
+ *   caller receives #DC_EVENT_OUTGOING_CALL_ACCEPTED.
+ *   callee's devices receive #DC_EVENT_INCOMING_CALL_ACCEPTED, call starts
+ *
+ * - callee rejects using dc_end_call():
+ *   caller receives #DC_EVENT_CALL_ENDED after 1 minute timeout.
+ *   callee's other devices receive #DC_EVENT_CALL_ENDED
+ *
+ * - callee is already in a call:
+ *   in this case, UI may decide to show a notification instead of ringing.
+ *   otherwise, this is same as timeout
+ *
+ * - timeout:
+ *   after 1 minute without action,
+ *   caller and callee receive #DC_EVENT_CALL_ENDED
+ *   to prevent endless ringing of callee
+ *   in case caller got offline without being able to send cancellation message
+ *
+ * Actions during the call:
+ *
+ * - caller ends the call using dc_end_call():
+ *   callee receives #DC_EVENT_CALL_ENDED
+ *
+ * - callee ends the call using dc_end_call():
+ *   caller receives #DC_EVENT_CALL_ENDED
+ *
+ * Note, that the events are for updating the call screen,
+ * possible status messages are added and updated as usual, including the known events.
+ * In the UI, the sorted chatlist is used as an overview about calls as well as messages.
+ * To place a call with a contact that has no chat yet, use dc_create_chat_by_contact_id() first.
+ *
+ * UI will usually allow only one call at the same time,
+ * this has to be tracked by UI across profile, the core does not track this.
+ *
+ * @memberof dc_context_t
+ * @param context The context object.
+ * @param chat_id The chat to place a call for.
+ *     This needs to be a one-to-one chat.
+ * @param place_call_info any data that other devices receive
+ *     in #DC_EVENT_INCOMING_CALL.
+ * @return ID of the system message announcing the call.
+ */
+uint32_t        dc_place_outgoing_call       (dc_context_t* context, uint32_t chat_id, const char* place_call_info);
+
+
+/**
+ * Accept incoming call.
+ *
+ * This implicitly accepts the contact request, if not yet done.
+ * All affected devices will receive
+ * either #DC_EVENT_OUTGOING_CALL_ACCEPTED or #DC_EVENT_INCOMING_CALL_ACCEPTED.
+ *
+ * @memberof dc_context_t
+ * @param context The context object.
+ * @param msg_id The ID of the call to accept.
+ *     This is the ID reported by #DC_EVENT_INCOMING_CALL
+ *     and equals to the ID of the corresponding info message.
+ * @param accept_call_info any data that other devices receive
+ *     in #DC_EVENT_OUTGOING_CALL_ACCEPTED or #DC_EVENT_INCOMING_CALL_ACCEPTED.
+ * @return 1=success, 0=error
+ */
+ int            dc_accept_incoming_call      (dc_context_t* context, uint32_t msg_id, const char* accept_call_info);
+
+
+ /**
+  * End incoming or outgoing call.
+  *
+  * From the view of the caller, a "cancellation",
+  * from the view of callee, a "rejection".
+  * If the call was accepted, this is a "hangup".
+  *
+  * For accepted calls,
+  * all participant devices get informed about the ended call via #DC_EVENT_CALL_ENDED.
+  * For not accepted calls, only the caller will inform the callee.
+  *
+  * If the callee rejects, the caller will get a timeout or give up at some point -
+  * same as for all other reasons the call cannot be established: Device not in reach, device muted, connectivity etc.
+  * This is to protect privacy of the callee, avoiding to check if callee is online.
+  *
+  * @memberof dc_context_t
+  * @param context The context object.
+  * @param msg_id the ID of the call.
+  * @return 1=success, 0=error
+  */
+ int            dc_end_call                  (dc_context_t* context, uint32_t msg_id);
+
+
 /**
  * Save a draft for a chat in the database.
  *
@@ -4546,6 +4643,8 @@ int             dc_msg_is_info                (const dc_msg_t* msg);
  *   and also offer a way to fix the encryption, eg. by a button offering a QR scan
  * - DC_INFO_WEBXDC_INFO_MESSAGE (32) - Info-message created by webxdc app sending `update.info`
  * - DC_INFO_CHAT_E2EE (50) - Info-message for "Chat is end-to-end-encrypted"
+ * - DC_INFO_OUTGOING_CALL (60) - Info-message refers to an outgoing call
+ * - DC_INFO_INCOMING_CALL (65) - Info-message refers to an incoming call
  *
  * For the messages that refer to a CONTACT,
  * dc_msg_get_info_contact_id() returns the contact ID.
@@ -4602,6 +4701,8 @@ uint32_t        dc_msg_get_info_contact_id    (const dc_msg_t* msg);
 #define         DC_INFO_INVALID_UNENCRYPTED_MAIL  13
 #define         DC_INFO_WEBXDC_INFO_MESSAGE       32
 #define         DC_INFO_CHAT_E2EE                 50
+#define         DC_INFO_OUTGOING_CALL             60
+#define         DC_INFO_INCOMING_CALL             65
 
 
 /**
@@ -6636,6 +6737,63 @@ void dc_event_unref(dc_event_t* event);
  */
 #define DC_EVENT_CHANNEL_OVERFLOW              2400
 
+
+
+/**
+ * Incoming call.
+ * UI will usually start ringing,
+ * or show a notification if there is already a call in some profile.
+ *
+ * Together with this event,
+ * an info-message is added to the corresponding chat.
+ * The info-message, however, is _not_ additionally notified using #DC_EVENT_INCOMING_MSG,
+ * if needed, this has to be done by the UI explicitly.
+ *
+ * If user takes action, dc_accept_incoming_call() or dc_end_call() should be called.
+ *
+ * Otherwise, ringing should end on #DC_EVENT_CALL_ENDED
+ * or #DC_EVENT_INCOMING_CALL_ACCEPTED
+ *
+ * @param data1 (int) msg_id ID of the info-message referring to the call.
+ * @param data2 (char*) place_call_info, text passed to dc_place_outgoing_call()
+ */
+#define DC_EVENT_INCOMING_CALL                            2550
+
+/**
+ * The callee accepted an incoming call on another device using dc_accept_incoming_call().
+ * The caller gets the event #DC_EVENT_OUTGOING_CALL_ACCEPTED at the same time.
+ *
+ * The event is sent unconditionally when the corresponding message is received.
+ * UI should only take action in case call UI was opened before, otherwise the event should be ignored.
+ *
+ * @param data1 (int) msg_id ID of the info-message referring to the call
+ * @param data2 (char*) accept_call_info, text passed to dc_place_outgoing_call()
+ */
+ #define DC_EVENT_INCOMING_CALL_ACCEPTED                  2560
+
+/**
+ * A call placed using dc_place_outgoing_call() was accepted by the callee using dc_accept_incoming_call().
+ *
+ * The event is sent unconditionally when the corresponding message is received.
+ * UI should only take action in case call UI was opened before, otherwise the event should be ignored.
+ *
+ * @param data1 (int) msg_id ID of the info-message referring to the call
+ * @param data2 (char*) accept_call_info, text passed to dc_accept_incoming_call()
+ */
+#define DC_EVENT_OUTGOING_CALL_ACCEPTED                   2570
+
+/**
+ * An incoming or outgoing call was ended using dc_end_call().
+ * Moreover, the event is sent when the call was not accepted within 1 minute timeout.
+ *
+ * The event is sent unconditionally when the corresponding message is received.
+ * UI should only take action in case call UI was opened before, otherwise the event should be ignored.
+ *
+ * @param data1 (int) msg_id ID of the info-message referring to the call
+ */
+#define DC_EVENT_CALL_ENDED                               2580
+
+
 /**
  * @}
  */

deltachat-ffi/src/lib.rs

@@ -556,6 +556,10 @@ pub unsafe extern "C" fn dc_event_get_id(event: *mut dc_event_t) -> libc::c_int
         EventType::AccountsChanged => 2302,
         EventType::AccountsItemChanged => 2303,
         EventType::EventChannelOverflow { .. } => 2400,
+        EventType::IncomingCall { .. } => 2550,
+        EventType::IncomingCallAccepted { .. } => 2560,
+        EventType::OutgoingCallAccepted { .. } => 2570,
+        EventType::CallEnded { .. } => 2580,
         #[allow(unreachable_patterns)]
         #[cfg(test)]
         _ => unreachable!("This is just to silence a rust_analyzer false-positive"),
@@ -619,7 +623,11 @@ pub unsafe extern "C" fn dc_event_get_data1_int(event: *mut dc_event_t) -> libc:
         EventType::WebxdcRealtimeData { msg_id, .. }
         | EventType::WebxdcStatusUpdate { msg_id, .. }
         | EventType::WebxdcRealtimeAdvertisementReceived { msg_id }
-        | EventType::WebxdcInstanceDeleted { msg_id, .. } => msg_id.to_u32() as libc::c_int,
+        | EventType::WebxdcInstanceDeleted { msg_id, .. }
+        | EventType::IncomingCall { msg_id, .. }
+        | EventType::IncomingCallAccepted { msg_id, .. }
+        | EventType::OutgoingCallAccepted { msg_id, .. }
+        | EventType::CallEnded { msg_id, .. } => msg_id.to_u32() as libc::c_int,
         EventType::ChatlistItemChanged { chat_id } => {
             chat_id.unwrap_or_default().to_u32() as libc::c_int
         }
@@ -671,6 +679,10 @@ pub unsafe extern "C" fn dc_event_get_data2_int(event: *mut dc_event_t) -> libc:
         | EventType::ChatModified(_)
         | EventType::ChatDeleted { .. }
         | EventType::WebxdcRealtimeAdvertisementReceived { .. }
+        | EventType::IncomingCall { .. }
+        | EventType::IncomingCallAccepted { .. }
+        | EventType::OutgoingCallAccepted { .. }
+        | EventType::CallEnded { .. }
         | EventType::EventChannelOverflow { .. } => 0,
         EventType::MsgsChanged { msg_id, .. }
         | EventType::ReactionsChanged { msg_id, .. }
@@ -767,8 +779,23 @@ pub unsafe extern "C" fn dc_event_get_data2_str(event: *mut dc_event_t) -> *mut
         | EventType::ChatlistChanged
         | EventType::AccountsChanged
         | EventType::AccountsItemChanged
-        | EventType::WebxdcRealtimeAdvertisementReceived { .. }
-        | EventType::EventChannelOverflow { .. } => ptr::null_mut(),
+        | EventType::WebxdcRealtimeAdvertisementReceived { .. } => ptr::null_mut(),
+        EventType::IncomingCall {
+            place_call_info, ..
+        } => {
+            let data2 = place_call_info.to_c_string().unwrap_or_default();
+            data2.into_raw()
+        }
+        EventType::IncomingCallAccepted {
+            accept_call_info, ..
+        }
+        | EventType::OutgoingCallAccepted {
+            accept_call_info, ..
+        } => {
+            let data2 = accept_call_info.to_c_string().unwrap_or_default();
+            data2.into_raw()
+        }
+        EventType::CallEnded { .. } | EventType::EventChannelOverflow { .. } => ptr::null_mut(),
         EventType::ConfigureProgress { comment, .. } => {
             if let Some(comment) = comment {
                 comment.to_c_string().unwrap_or_default().into_raw()
@@ -1167,6 +1194,61 @@ pub unsafe extern "C" fn dc_init_webxdc_integration(
         .unwrap_or(0)
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_place_outgoing_call(
+    context: *mut dc_context_t,
+    chat_id: u32,
+    place_call_info: *const libc::c_char,
+) -> u32 {
+    if context.is_null() || chat_id == 0 {
+        eprintln!("ignoring careless call to dc_place_outgoing_call()");
+        return 0;
+    }
+    let ctx = &*context;
+    let chat_id = ChatId::new(chat_id);
+    let place_call_info = to_string_lossy(place_call_info);
+
+    block_on(ctx.place_outgoing_call(chat_id, place_call_info))
+        .context("Failed to place call")
+        .log_err(ctx)
+        .map(|msg_id| msg_id.to_u32())
+        .unwrap_or_log_default(ctx, "Failed to place call")
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dc_accept_incoming_call(
+    context: *mut dc_context_t,
+    msg_id: u32,
+    accept_call_info: *const libc::c_char,
+) -> libc::c_int {
+    if context.is_null() || msg_id == 0 {
+        eprintln!("ignoring careless call to dc_accept_incoming_call()");
+        return 0;
+    }
+    let ctx = &*context;
+    let msg_id = MsgId::new(msg_id);
+    let accept_call_info = to_string_lossy(accept_call_info);
+
+    block_on(ctx.accept_incoming_call(msg_id, accept_call_info))
+        .context("Failed to accept call")
+        .is_ok() as libc::c_int
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dc_end_call(context: *mut dc_context_t, msg_id: u32) -> libc::c_int {
+    if context.is_null() || msg_id == 0 {
+        eprintln!("ignoring careless call to dc_end_call()");
+        return 0;
+    }
+    let ctx = &*context;
+    let msg_id = MsgId::new(msg_id);
+
+    block_on(ctx.end_call(msg_id))
+        .context("Failed to end call")
+        .log_err(ctx)
+        .is_ok() as libc::c_int
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_set_draft(
     context: *mut dc_context_t,

deltachat-jsonrpc/src/api/types/events.rs

@@ -416,6 +416,37 @@ pub enum EventType {
         /// Number of events skipped.
         n: u64,
     },
+
+    /// Incoming call.
+    IncomingCall {
+        /// ID of the info message referring to the call.
+        msg_id: u32,
+        /// User-defined info as passed to place_outgoing_call()
+        place_call_info: String,
+    },
+
+    /// Incoming call accepted.
+    /// This is esp. interesting to stop ringing on other devices.
+    IncomingCallAccepted {
+        /// ID of the info message referring to the call.
+        msg_id: u32,
+        /// User-defined info passed to dc_accept_incoming_call()
+        accept_call_info: String,
+    },
+
+    /// Outgoing call accepted.
+    OutgoingCallAccepted {
+        /// ID of the info message referring to the call.
+        msg_id: u32,
+        /// User-defined info passed to dc_accept_incoming_call(
+        accept_call_info: String,
+    },
+
+    /// Call ended.
+    CallEnded {
+        /// ID of the info message referring to the call.
+        msg_id: u32,
+    },
 }
 
 impl From<CoreEventType> for EventType {
@@ -566,6 +597,30 @@ impl From<CoreEventType> for EventType {
             CoreEventType::EventChannelOverflow { n } => EventChannelOverflow { n },
             CoreEventType::AccountsChanged => AccountsChanged,
             CoreEventType::AccountsItemChanged => AccountsItemChanged,
+            CoreEventType::IncomingCall {
+                msg_id,
+                place_call_info,
+            } => IncomingCall {
+                msg_id: msg_id.to_u32(),
+                place_call_info,
+            },
+            CoreEventType::IncomingCallAccepted {
+                msg_id,
+                accept_call_info,
+            } => IncomingCallAccepted {
+                msg_id: msg_id.to_u32(),
+                accept_call_info,
+            },
+            CoreEventType::OutgoingCallAccepted {
+                msg_id,
+                accept_call_info,
+            } => OutgoingCallAccepted {
+                msg_id: msg_id.to_u32(),
+                accept_call_info,
+            },
+            CoreEventType::CallEnded { msg_id } => CallEnded {
+                msg_id: msg_id.to_u32(),
+            },
             #[allow(unreachable_patterns)]
             #[cfg(test)]
             _ => unreachable!("This is just to silence a rust_analyzer false-positive"),

deltachat-jsonrpc/src/api/types/message.rs

@@ -437,6 +437,11 @@ pub enum SystemMessageType {
 
     /// This message contains a users iroh node address.
     IrohNodeAddr,
+
+    OutgoingCall,
+    IncomingCall,
+    CallAccepted,
+    CallEnded,
 }
 
 impl From<deltachat::mimeparser::SystemMessage> for SystemMessageType {
@@ -463,6 +468,10 @@ impl From<deltachat::mimeparser::SystemMessage> for SystemMessageType {
             SystemMessage::IrohNodeAddr => SystemMessageType::IrohNodeAddr,
             SystemMessage::SecurejoinWait => SystemMessageType::SecurejoinWait,
             SystemMessage::SecurejoinWaitTimeout => SystemMessageType::SecurejoinWaitTimeout,
+            SystemMessage::OutgoingCall => SystemMessageType::OutgoingCall,
+            SystemMessage::IncomingCall => SystemMessageType::IncomingCall,
+            SystemMessage::CallAccepted => SystemMessageType::CallAccepted,
+            SystemMessage::CallEnded => SystemMessageType::CallEnded,
         }
     }
 }

python/tests/test_1_online.py

@@ -160,32 +160,6 @@ def test_html_message(acfactory, lp):
     assert html_text in msg2.html
 
 
-def test_videochat_invitation_message(acfactory, lp):
-    ac1, ac2 = acfactory.get_online_accounts(2)
-    chat = acfactory.get_accepted_chat(ac1, ac2)
-    text = "You are invited to a video chat, click https://meet.jit.si/WxEGad0gGzX to join."
-
-    lp.sec("ac1: prepare and send text message to ac2")
-    msg1 = chat.send_text("message0")
-    assert not msg1.is_videochat_invitation()
-
-    lp.sec("wait for ac2 to receive message")
-    msg2 = ac2._evtracker.wait_next_incoming_message()
-    assert msg2.text == "message0"
-    assert not msg2.is_videochat_invitation()
-
-    lp.sec("ac1: prepare and send videochat invitation to ac2")
-    msg1 = Message.new_empty(ac1, "videochat")
-    msg1.set_text(text)
-    msg1 = chat.send_msg(msg1)
-    assert msg1.is_videochat_invitation()
-
-    lp.sec("wait for ac2 to receive message")
-    msg2 = ac2._evtracker.wait_next_incoming_message()
-    assert msg2.text == text
-    assert msg2.is_videochat_invitation()
-
-
 def test_webxdc_message(acfactory, data, lp):
     ac1, ac2 = acfactory.get_online_accounts(2)
     chat = acfactory.get_accepted_chat(ac1, ac2)

src/calls.rs

@@ -0,0 +1,307 @@
+//! # Handle calls.
+//!
+//! Internally, calls are bound to the user-visible info message initializing the call.
+//! This means, the "Call ID" is a "Message ID" currently - similar to webxdc.
+use crate::chat::{Chat, ChatId, send_msg};
+use crate::constants::Chattype;
+use crate::context::Context;
+use crate::events::EventType;
+use crate::headerdef::HeaderDef;
+use crate::message::{self, Message, MsgId, Viewtype, rfc724_mid_exists};
+use crate::mimeparser::{MimeMessage, SystemMessage};
+use crate::param::Param;
+use crate::sync::SyncData;
+use crate::tools::time;
+use anyhow::{Result, ensure};
+use std::time::Duration;
+use tokio::task;
+use tokio::time::sleep;
+
+/// How long callee's or caller's phone ring.
+///
+/// For the callee, this is to prevent endless ringing
+/// in case the initial "call" is received, but then the caller went offline.
+/// Moreover, this prevents outdated calls to ring
+/// in case the initial "call" message arrives delayed.
+///
+/// For the caller, this means they should also not wait longer,
+/// as the callee won't start the call afterwards.
+const RINGING_SECONDS: i64 = 60;
+
+/// Information about the status of a call.
+#[derive(Debug, Default)]
+pub struct CallInfo {
+    /// Incoming or outgoing call?
+    pub is_incoming: bool,
+
+    /// Was an incoming call accepted on this device?
+    /// For privacy reasons, only for accepted incoming calls, callee sends a message to caller on `end_call()`.
+    /// On other devices and for outgoing calls, `is_accepted` is never set.
+    pub is_accepted: bool,
+
+    /// User-defined text as given to place_outgoing_call()
+    pub place_call_info: String,
+
+    /// User-defined text as given to accept_incoming_call()
+    pub accept_call_info: String,
+
+    /// Info message referring to the call.
+    pub msg: Message,
+}
+
+impl CallInfo {
+    fn is_stale_call(&self) -> bool {
+        self.remaining_ring_seconds() <= 0
+    }
+
+    fn remaining_ring_seconds(&self) -> i64 {
+        let remaining_seconds = self.msg.timestamp_sent + RINGING_SECONDS - time();
+        remaining_seconds.clamp(0, RINGING_SECONDS)
+    }
+
+    async fn update_text(&self, context: &Context, text: &str) -> Result<()> {
+        context
+            .sql
+            .execute(
+                "UPDATE msgs SET txt=?, txt_normalized=? WHERE id=?",
+                (text, message::normalize_text(text), self.msg.id),
+            )
+            .await?;
+        Ok(())
+    }
+}
+
+impl Context {
+    /// Start an outgoing call.
+    pub async fn place_outgoing_call(
+        &self,
+        chat_id: ChatId,
+        place_call_info: String,
+    ) -> Result<MsgId> {
+        let chat = Chat::load_from_db(self, chat_id).await?;
+        ensure!(chat.typ == Chattype::Single && !chat.is_self_talk());
+
+        let mut call = Message {
+            viewtype: Viewtype::Text,
+            text: "Calling...".into(),
+            ..Default::default()
+        };
+        call.param.set_cmd(SystemMessage::OutgoingCall);
+        call.param.set(Param::WebrtcRoom, &place_call_info);
+        call.id = send_msg(self, chat_id, &mut call).await?;
+
+        let wait = RINGING_SECONDS;
+        task::spawn(Context::emit_end_call_if_unaccepted(
+            self.clone(),
+            wait.try_into()?,
+            call.id,
+        ));
+
+        Ok(call.id)
+    }
+
+    /// Accept an incoming call.
+    pub async fn accept_incoming_call(
+        &self,
+        call_id: MsgId,
+        accept_call_info: String,
+    ) -> Result<()> {
+        let mut call: CallInfo = self.load_call_by_id(call_id).await?;
+        ensure!(call.is_incoming);
+
+        let chat = Chat::load_from_db(self, call.msg.chat_id).await?;
+        if chat.is_contact_request() {
+            chat.id.accept(self).await?;
+        }
+
+        call.msg
+            .mark_call_as_accepted(self, accept_call_info.to_string())
+            .await?;
+
+        // send an acceptance message around: to the caller as well as to the other devices of the callee
+        let mut msg = Message {
+            viewtype: Viewtype::Text,
+            text: "Call accepted".into(),
+            ..Default::default()
+        };
+        msg.param.set_cmd(SystemMessage::CallAccepted);
+        msg.param
+            .set(Param::WebrtcAccepted, accept_call_info.to_string());
+        msg.set_quote(self, Some(&call.msg)).await?;
+        msg.id = send_msg(self, call.msg.chat_id, &mut msg).await?;
+        self.emit_event(EventType::IncomingCallAccepted {
+            msg_id: call.msg.id,
+            accept_call_info,
+        });
+        Ok(())
+    }
+
+    /// Cancel, reject or hangup an incoming or outgoing call.
+    pub async fn end_call(&self, call_id: MsgId) -> Result<()> {
+        let call: CallInfo = self.load_call_by_id(call_id).await?;
+
+        if call.is_accepted || !call.is_incoming {
+            let mut msg = Message {
+                viewtype: Viewtype::Text,
+                text: "Call ended".into(),
+                ..Default::default()
+            };
+            msg.param.set_cmd(SystemMessage::CallEnded);
+            msg.set_quote(self, Some(&call.msg)).await?;
+            msg.id = send_msg(self, call.msg.chat_id, &mut msg).await?;
+        } else if call.is_incoming {
+            // to protect privacy, we do not send a message to others from callee for unaccepted calls
+            self.add_sync_item(SyncData::RejectIncomingCall {
+                msg: call.msg.rfc724_mid,
+            })
+            .await?;
+            self.scheduler.interrupt_inbox().await;
+        }
+
+        self.emit_event(EventType::CallEnded {
+            msg_id: call.msg.id,
+        });
+        Ok(())
+    }
+
+    async fn emit_end_call_if_unaccepted(
+        context: Context,
+        wait: u64,
+        call_id: MsgId,
+    ) -> Result<()> {
+        sleep(Duration::from_secs(wait)).await;
+        let call = context.load_call_by_id(call_id).await?;
+        if !call.is_accepted {
+            context.emit_event(EventType::CallEnded {
+                msg_id: call.msg.id,
+            });
+        }
+        Ok(())
+    }
+
+    pub(crate) async fn handle_call_msg(
+        &self,
+        mime_message: &MimeMessage,
+        call_id: MsgId,
+    ) -> Result<()> {
+        match mime_message.is_system_message {
+            SystemMessage::IncomingCall => {
+                let call = self.load_call_by_id(call_id).await?;
+                if call.is_incoming {
+                    if call.is_stale_call() {
+                        call.update_text(self, "Missed call").await?;
+                        self.emit_incoming_msg(call.msg.chat_id, call_id);
+                    } else {
+                        self.emit_msgs_changed(call.msg.chat_id, call_id);
+                        self.emit_event(EventType::IncomingCall {
+                            msg_id: call.msg.id,
+                            place_call_info: call.place_call_info.to_string(),
+                        });
+                        let wait = call.remaining_ring_seconds();
+                        task::spawn(Context::emit_end_call_if_unaccepted(
+                            self.clone(),
+                            wait.try_into()?,
+                            call.msg.id,
+                        ));
+                    }
+                } else {
+                    self.emit_msgs_changed(call.msg.chat_id, call_id);
+                }
+            }
+            SystemMessage::CallAccepted => {
+                let call = self.load_call_by_id(call_id).await?;
+                self.emit_msgs_changed(call.msg.chat_id, call_id);
+                if call.is_incoming {
+                    self.emit_event(EventType::IncomingCallAccepted {
+                        msg_id: call.msg.id,
+                        accept_call_info: call.accept_call_info,
+                    });
+                } else {
+                    let accept_call_info = mime_message
+                        .get_header(HeaderDef::ChatWebrtcAccepted)
+                        .unwrap_or_default();
+                    call.msg
+                        .clone()
+                        .mark_call_as_accepted(self, accept_call_info.to_string())
+                        .await?;
+                    self.emit_event(EventType::OutgoingCallAccepted {
+                        msg_id: call.msg.id,
+                        accept_call_info: accept_call_info.to_string(),
+                    });
+                }
+            }
+            SystemMessage::CallEnded => {
+                let call = self.load_call_by_id(call_id).await?;
+                self.emit_msgs_changed(call.msg.chat_id, call_id);
+                self.emit_event(EventType::CallEnded {
+                    msg_id: call.msg.id,
+                });
+            }
+            _ => {}
+        }
+        Ok(())
+    }
+
+    pub(crate) async fn sync_call_rejection(&self, rfc724_mid: &str) -> Result<()> {
+        if let Some((msg_id, _)) = rfc724_mid_exists(self, rfc724_mid).await? {
+            self.emit_event(EventType::CallEnded { msg_id });
+        }
+        Ok(())
+    }
+
+    async fn load_call_by_id(&self, call_id: MsgId) -> Result<CallInfo> {
+        let call = Message::load_from_db(self, call_id).await?;
+        self.load_call_by_message(call)
+    }
+
+    fn load_call_by_message(&self, call: Message) -> Result<CallInfo> {
+        ensure!(
+            call.get_info_type() == SystemMessage::IncomingCall
+                || call.get_info_type() == SystemMessage::OutgoingCall
+        );
+
+        Ok(CallInfo {
+            is_incoming: call.get_info_type() == SystemMessage::IncomingCall,
+            is_accepted: call.is_call_accepted()?,
+            place_call_info: call
+                .param
+                .get(Param::WebrtcRoom)
+                .unwrap_or_default()
+                .to_string(),
+            accept_call_info: call
+                .param
+                .get(Param::WebrtcAccepted)
+                .unwrap_or_default()
+                .to_string(),
+            msg: call,
+        })
+    }
+}
+
+impl Message {
+    async fn mark_call_as_accepted(
+        &mut self,
+        context: &Context,
+        accept_call_info: String,
+    ) -> Result<()> {
+        ensure!(
+            self.get_info_type() == SystemMessage::IncomingCall
+                || self.get_info_type() == SystemMessage::OutgoingCall
+        );
+        self.param.set_int(Param::Arg, 1);
+        self.param.set(Param::WebrtcAccepted, accept_call_info);
+        self.update_param(context).await?;
+        Ok(())
+    }
+
+    fn is_call_accepted(&self) -> Result<bool> {
+        ensure!(
+            self.get_info_type() == SystemMessage::IncomingCall
+                || self.get_info_type() == SystemMessage::OutgoingCall
+        );
+        Ok(self.param.get_int(Param::Arg) == Some(1))
+    }
+}
+
+#[cfg(test)]
+mod calls_tests;

src/calls/calls_tests.rs

@@ -0,0 +1,372 @@
+use super::*;
+use crate::config::Config;
+use crate::test_utils::{TestContext, TestContextManager, sync};
+
+struct CallSetup {
+    pub alice: TestContext,
+    pub alice2: TestContext,
+    pub alice_call: Message,
+    pub bob: TestContext,
+    pub bob2: TestContext,
+    pub bob_call: Message,
+    pub bob2_call: Message,
+}
+
+async fn setup_call() -> Result<CallSetup> {
+    let mut tcm = TestContextManager::new();
+    let alice = tcm.alice().await;
+    let alice2 = tcm.alice().await;
+    let bob = tcm.bob().await;
+    let bob2 = tcm.bob().await;
+    for t in [&alice, &alice2, &bob, &bob2] {
+        t.set_config_bool(Config::SyncMsgs, true).await?;
+    }
+
+    // Alice creates a chat with Bob and places an outgoing call there.
+    // Alice's other device sees the same message as an outgoing call.
+    let alice_chat = alice.create_chat(&bob).await;
+    let test_msg_id = alice
+        .place_outgoing_call(alice_chat.id, "place_info".to_string())
+        .await?;
+    let sent1 = alice.pop_sent_msg().await;
+    assert_eq!(sent1.sender_msg_id, test_msg_id);
+    let alice_call = Message::load_from_db(&alice, sent1.sender_msg_id).await?;
+    let alice2_call = alice2.recv_msg(&sent1).await;
+    for (t, m) in [(&alice, &alice_call), (&alice2, &alice2_call)] {
+        assert!(m.is_info());
+        assert_eq!(m.get_info_type(), SystemMessage::OutgoingCall);
+        let info = t.load_call_by_id(m.id).await?;
+        assert!(!info.is_accepted);
+        assert_eq!(info.place_call_info, "place_info");
+    }
+
+    // Bob receives the message referring to the call on two devices;
+    // it is an incoming call from the view of Bob
+    let bob_call = bob.recv_msg(&sent1).await;
+    let bob2_call = bob2.recv_msg(&sent1).await;
+    for (t, m) in [(&bob, &bob_call), (&bob2, &bob2_call)] {
+        assert!(m.is_info());
+        assert_eq!(m.get_info_type(), SystemMessage::IncomingCall);
+        t.evtracker
+            .get_matching(|evt| matches!(evt, EventType::IncomingCall { .. }))
+            .await;
+        let info = t.load_call_by_id(m.id).await?;
+        assert!(!info.is_accepted);
+        assert_eq!(info.place_call_info, "place_info");
+    }
+
+    Ok(CallSetup {
+        alice,
+        alice2,
+        alice_call,
+        bob,
+        bob2,
+        bob_call,
+        bob2_call,
+    })
+}
+
+async fn accept_call() -> Result<CallSetup> {
+    let CallSetup {
+        alice,
+        alice2,
+        alice_call,
+        bob,
+        bob2,
+        bob_call,
+        bob2_call,
+    } = setup_call().await?;
+
+    // Bob accepts the incoming call, this does not add an additional message to the chat
+    bob.accept_incoming_call(bob_call.id, "accepted_info".to_string())
+        .await?;
+    bob.evtracker
+        .get_matching(|evt| matches!(evt, EventType::IncomingCallAccepted { .. }))
+        .await;
+    let sent2 = bob.pop_sent_msg().await;
+    let info = bob.load_call_by_id(bob_call.id).await?;
+    assert!(info.is_accepted);
+    assert_eq!(info.place_call_info, "place_info");
+    assert_eq!(info.accept_call_info, "accepted_info");
+
+    let bob_accept_msg = bob2.recv_msg(&sent2).await;
+    assert!(bob_accept_msg.is_info());
+    assert_eq!(bob_accept_msg.get_info_type(), SystemMessage::CallAccepted);
+    bob2.evtracker
+        .get_matching(|evt| matches!(evt, EventType::IncomingCallAccepted { .. }))
+        .await;
+    let info = bob2.load_call_by_id(bob2_call.id).await?;
+    assert!(!info.is_accepted); // "accepted" is only true on the device that does the call
+
+    // Alice receives the acceptance message
+    let alice_accept_msg = alice.recv_msg(&sent2).await;
+    assert!(alice_accept_msg.is_info());
+    assert_eq!(
+        alice_accept_msg.get_info_type(),
+        SystemMessage::CallAccepted
+    );
+    alice
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::OutgoingCallAccepted { .. }))
+        .await;
+    let info = alice.load_call_by_id(alice_call.id).await?;
+    assert!(info.is_accepted);
+    assert_eq!(info.place_call_info, "place_info");
+    assert_eq!(info.accept_call_info, "accepted_info");
+
+    let alice2_accept_msg = alice2.recv_msg(&sent2).await;
+    assert!(alice2_accept_msg.is_info());
+    assert_eq!(
+        alice2_accept_msg.get_info_type(),
+        SystemMessage::CallAccepted
+    );
+    alice2
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::OutgoingCallAccepted { .. }))
+        .await;
+
+    Ok(CallSetup {
+        alice,
+        alice2,
+        alice_call,
+        bob,
+        bob2,
+        bob_call,
+        bob2_call,
+    })
+}
+
+fn assert_is_call_ended_info_msg(msg: Message) {
+    assert!(msg.is_info());
+    assert_eq!(msg.get_info_type(), SystemMessage::CallEnded);
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_accept_call_callee_ends() -> Result<()> {
+    // Alice calls Bob, Bob accepts
+    let CallSetup {
+        alice,
+        alice2,
+        bob,
+        bob2,
+        bob_call,
+        ..
+    } = accept_call().await?;
+
+    // Bob has accepted the call and also ends it
+    bob.end_call(bob_call.id).await?;
+    bob.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+    let sent3 = bob.pop_sent_msg().await;
+
+    let bob2_end_call_msg = bob2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(bob2_end_call_msg);
+    bob2.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    // Alice receives the ending message
+    let alice_end_call_msg = alice.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(alice_end_call_msg);
+    alice
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    let alice2_end_call_msg = alice2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(alice2_end_call_msg);
+    alice2
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_accept_call_caller_ends() -> Result<()> {
+    // Alice calls Bob, Bob accepts
+    let CallSetup {
+        alice,
+        alice2,
+        bob,
+        bob2,
+        bob_call,
+        ..
+    } = accept_call().await?;
+
+    // Bob has accepted the call but Alice ends it
+    alice.end_call(bob_call.id).await?;
+    alice
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+    let sent3 = alice.pop_sent_msg().await;
+
+    let alice2_end_call_msg = alice2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(alice2_end_call_msg);
+    alice2
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    // Bob receives the ending message
+    let bob_end_call_msg = bob.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(bob_end_call_msg);
+    bob.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    let bob2_end_call_msg = bob2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(bob2_end_call_msg);
+    bob2.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_callee_rejects_call() -> Result<()> {
+    // Alice calls Bob
+    let CallSetup {
+        bob,
+        bob2,
+        bob_call,
+        ..
+    } = setup_call().await?;
+
+    // Bob does not want to talk with Alice.
+    // To protect Bob's privacy, no message is sent to Alice (who will time out).
+    // To let Bob close the call window on all devices, a sync message is used instead.
+    bob.end_call(bob_call.id).await?;
+    bob.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    sync(&bob, &bob2).await;
+    bob2.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_caller_cancels_call() -> Result<()> {
+    // Alice calls Bob
+    let CallSetup {
+        alice,
+        alice2,
+        alice_call,
+        bob,
+        bob2,
+        ..
+    } = setup_call().await?;
+
+    // Alice changes their mind before Bob picks up
+    alice.end_call(alice_call.id).await?;
+    alice
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+    let sent3 = alice.pop_sent_msg().await;
+
+    let alice2_call_ended_msg = alice2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(alice2_call_ended_msg);
+    alice2
+        .evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    // Bob receives the ending message
+    let bob_call_ended_msg = bob.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(bob_call_ended_msg);
+    bob.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    let bob2_call_ended_msg = bob2.recv_msg(&sent3).await;
+    assert_is_call_ended_info_msg(bob2_call_ended_msg);
+    bob2.evtracker
+        .get_matching(|evt| matches!(evt, EventType::CallEnded { .. }))
+        .await;
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_is_stale_call() -> Result<()> {
+    // a call started now is not stale
+    let call_info = CallInfo {
+        msg: Message {
+            timestamp_sent: time(),
+            ..Default::default()
+        },
+        ..Default::default()
+    };
+    assert!(!call_info.is_stale_call());
+    let remaining_seconds = call_info.remaining_ring_seconds();
+    assert!(remaining_seconds == RINGING_SECONDS || remaining_seconds == RINGING_SECONDS - 1);
+
+    // call started 5 seconds ago, this is not stale as well
+    let call_info = CallInfo {
+        msg: Message {
+            timestamp_sent: time() - 5,
+            ..Default::default()
+        },
+        ..Default::default()
+    };
+    assert!(!call_info.is_stale_call());
+    let remaining_seconds = call_info.remaining_ring_seconds();
+    assert!(remaining_seconds == RINGING_SECONDS - 5 || remaining_seconds == RINGING_SECONDS - 6);
+
+    // a call started one hour ago is clearly stale
+    let call_info = CallInfo {
+        msg: Message {
+            timestamp_sent: time() - 3600,
+            ..Default::default()
+        },
+        ..Default::default()
+    };
+    assert!(call_info.is_stale_call());
+    assert_eq!(call_info.remaining_ring_seconds(), 0);
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_mark_call_as_accepted() -> Result<()> {
+    let CallSetup {
+        alice, alice_call, ..
+    } = setup_call().await?;
+    assert!(!alice_call.is_call_accepted()?);
+
+    let mut alice_call = Message::load_from_db(&alice, alice_call.id).await?;
+    assert!(!alice_call.is_call_accepted()?);
+    alice_call
+        .mark_call_as_accepted(&alice, "accepted_info".to_string())
+        .await?;
+    assert!(alice_call.is_call_accepted()?);
+
+    let alice_call = Message::load_from_db(&alice, alice_call.id).await?;
+    assert!(alice_call.is_call_accepted()?);
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_udpate_call_text() -> Result<()> {
+    let CallSetup {
+        alice, alice_call, ..
+    } = setup_call().await?;
+
+    let call_info = alice.load_call_by_id(alice_call.id).await?;
+    call_info.update_text(&alice, "foo bar").await?;
+
+    let alice_call = Message::load_from_db(&alice, alice_call.id).await?;
+    assert_eq!(alice_call.get_text(), "foo bar");
+
+    Ok(())
+}

src/events/payload.rs

@@ -376,6 +376,36 @@ pub enum EventType {
     /// This event is emitted from the account whose property changed.
     AccountsItemChanged,
 
+    /// Incoming call.
+    IncomingCall {
+        /// ID of the message referring to the call.
+        msg_id: MsgId,
+        /// User-defined info as passed to place_outgoing_call()
+        place_call_info: String,
+    },
+
+    /// Incoming call accepted.
+    IncomingCallAccepted {
+        /// ID of the message referring to the call.
+        msg_id: MsgId,
+        /// User-defined info as passed to accept_incoming_call()
+        accept_call_info: String,
+    },
+
+    /// Outgoing call accepted.
+    OutgoingCallAccepted {
+        /// ID of the message referring to the call.
+        msg_id: MsgId,
+        /// User-defined info as passed to accept_incoming_call()
+        accept_call_info: String,
+    },
+
+    /// Call ended.
+    CallEnded {
+        /// ID of the message referring to the call.
+        msg_id: MsgId,
+    },
+
     /// Event for using in tests, e.g. as a fence between normally generated events.
     #[cfg(test)]
     Test,

src/headerdef.rs

@@ -86,6 +86,7 @@ pub enum HeaderDef {
 
     ChatDispositionNotificationTo,
     ChatWebrtcRoom,
+    ChatWebrtcAccepted,
 
     /// This message deletes the messages listed in the value by rfc724_mid.
     ChatDelete,

src/lib.rs

@@ -53,6 +53,7 @@ pub use events::*;
 
 mod aheader;
 pub mod blob;
+pub mod calls;
 pub mod chat;
 pub mod chatlist;
 pub mod config;

src/message.rs

@@ -973,6 +973,10 @@ impl Message {
             | SystemMessage::WebxdcStatusUpdate
             | SystemMessage::WebxdcInfoMessage
             | SystemMessage::IrohNodeAddr
+            | SystemMessage::OutgoingCall
+            | SystemMessage::IncomingCall
+            | SystemMessage::CallAccepted
+            | SystemMessage::CallEnded
             | SystemMessage::Unknown => Ok(None),
         }
     }

src/mimefactory.rs

@@ -3,7 +3,7 @@
 use std::collections::{BTreeSet, HashSet};
 use std::io::Cursor;
 
-use anyhow::{Context as _, Result, bail, ensure};
+use anyhow::{Context as _, Result, anyhow, bail, ensure};
 use base64::Engine as _;
 use data_encoding::BASE32_NOPAD;
 use deltachat_contact_tools::sanitize_bidi_characters;
@@ -1533,6 +1533,27 @@ impl MimeFactory {
                     .into(),
                 ));
             }
+            SystemMessage::OutgoingCall => {
+                headers.push((
+                    "Chat-Content",
+                    mail_builder::headers::raw::Raw::new("call").into(),
+                ));
+            }
+            SystemMessage::IncomingCall => {
+                return Err(anyhow!("Unexpected incoming call rendering."));
+            }
+            SystemMessage::CallAccepted => {
+                headers.push((
+                    "Chat-Content",
+                    mail_builder::headers::raw::Raw::new("call-accepted").into(),
+                ));
+            }
+            SystemMessage::CallEnded => {
+                headers.push((
+                    "Chat-Content",
+                    mail_builder::headers::raw::Raw::new("call-ended").into(),
+                ));
+            }
             _ => {}
         }
 
@@ -1557,6 +1578,9 @@ impl MimeFactory {
                 "Chat-Content",
                 mail_builder::headers::raw::Raw::new("videochat-invitation").into(),
             ));
+        }
+
+        if msg.param.exists(Param::WebrtcRoom) {
             headers.push((
                 "Chat-Webrtc-Room",
                 mail_builder::headers::raw::Raw::new(
@@ -1567,6 +1591,17 @@ impl MimeFactory {
                 )
                 .into(),
             ));
+        } else if msg.param.exists(Param::WebrtcAccepted) {
+            headers.push((
+                "Chat-Webrtc-Accepted",
+                mail_builder::headers::raw::Raw::new(
+                    msg.param
+                        .get(Param::WebrtcAccepted)
+                        .unwrap_or_default()
+                        .to_string(),
+                )
+                .into(),
+            ));
         }
 
         if msg.viewtype == Viewtype::Voice

src/mimeparser.rs

@@ -216,6 +216,22 @@ pub enum SystemMessage {
 
     /// "Messages are end-to-end encrypted."
     ChatE2ee = 50,
+
+    /// This system message represents an outgoing call.
+    /// This message is visible to the user as an "info" message.
+    OutgoingCall = 60,
+
+    /// This system message represents an incoming call.
+    /// This message is visible to the user as an "info" message.
+    IncomingCall = 65,
+
+    /// Message indicating that a call was accepted.
+    /// While the 1:1 call may be established elsewhere,
+    /// the message is still needed for a multidevice setup, so that other devices stop ringing.
+    CallAccepted = 66,
+
+    /// Message indicating that a call was ended.
+    CallEnded = 67,
 }
 
 const MIME_AC_SETUP_FILE: &str = "application/autocrypt-setup";
@@ -676,6 +692,16 @@ impl MimeMessage {
                 self.is_system_message = SystemMessage::ChatProtectionDisabled;
             } else if value == "group-avatar-changed" {
                 self.is_system_message = SystemMessage::GroupImageChanged;
+            } else if value == "call" {
+                self.is_system_message = if self.incoming {
+                    SystemMessage::IncomingCall
+                } else {
+                    SystemMessage::OutgoingCall
+                };
+            } else if value == "call-accepted" {
+                self.is_system_message = SystemMessage::CallAccepted;
+            } else if value == "call-ended" {
+                self.is_system_message = SystemMessage::CallEnded;
             }
         } else if self.get_header(HeaderDef::ChatGroupMemberRemoved).is_some() {
             self.is_system_message = SystemMessage::MemberRemovedFromGroup;
@@ -698,16 +724,24 @@ impl MimeMessage {
     }
 
     fn parse_videochat_headers(&mut self) {
-        if let Some(value) = self.get_header(HeaderDef::ChatContent) {
-            if value == "videochat-invitation" {
-                let instance = self
-                    .get_header(HeaderDef::ChatWebrtcRoom)
-                    .map(|s| s.to_string());
-                if let Some(part) = self.parts.first_mut() {
+        let content = self
+            .get_header(HeaderDef::ChatContent)
+            .unwrap_or_default()
+            .to_string();
+        let room = self
+            .get_header(HeaderDef::ChatWebrtcRoom)
+            .map(|s| s.to_string());
+        let accepted = self
+            .get_header(HeaderDef::ChatWebrtcAccepted)
+            .map(|s| s.to_string());
+        if let Some(part) = self.parts.first_mut() {
+            if let Some(room) = room {
+                if content == "videochat-invitation" {
                     part.typ = Viewtype::VideochatInvitation;
-                    part.param
-                        .set(Param::WebrtcRoom, instance.unwrap_or_default());
                 }
+                part.param.set(Param::WebrtcRoom, room);
+            } else if let Some(accepted) = accepted {
+                part.param.set(Param::WebrtcAccepted, accepted);
             }
         }
     }

src/param.rs

@@ -120,6 +120,9 @@ pub enum Param {
     /// For Messages
     WebrtcRoom = b'V',
 
+    /// For Messages
+    WebrtcAccepted = b'7',
+
     /// For Messages: space-separated list of messaged IDs of forwarded copies.
     ///
     /// This is used when a [crate::message::Message] is in the

src/receive_imf.rs

@@ -1000,12 +1000,16 @@ pub(crate) async fn receive_imf_inner(
         }
     }
 
-    if received_msg.hidden {
+    if mime_parser.is_system_message == SystemMessage::IncomingCall {
+        context.handle_call_msg(&mime_parser, insert_msg_id).await?;
+    } else if received_msg.hidden {
         // No need to emit an event about the changed message
     } else if let Some(replace_chat_id) = replace_chat_id {
         context.emit_msgs_changed_without_msg_id(replace_chat_id);
     } else if !chat_id.is_trash() {
-        let fresh = received_msg.state == MessageState::InFresh;
+        let fresh = received_msg.state == MessageState::InFresh
+            && mime_parser.is_system_message != SystemMessage::CallAccepted
+            && mime_parser.is_system_message != SystemMessage::CallEnded;
         for msg_id in &received_msg.msg_ids {
             chat_id.emit_msg_event(context, *msg_id, mime_parser.incoming && fresh);
         }
@@ -1998,6 +2002,22 @@ async fn add_parts(
 
     handle_edit_delete(context, mime_parser, from_id).await?;
 
+    if mime_parser.is_system_message == SystemMessage::CallAccepted
+        || mime_parser.is_system_message == SystemMessage::CallEnded
+    {
+        if let Some(field) = mime_parser.get_header(HeaderDef::InReplyTo) {
+            if let Some(call) =
+                message::get_by_rfc724_mids(context, &parse_message_ids(field)).await?
+            {
+                context.handle_call_msg(mime_parser, call.get_id()).await?;
+            } else {
+                warn!(context, "Call: Cannot load parent.")
+            }
+        } else {
+            warn!(context, "Call: Not a reply.")
+        }
+    }
+
     let hidden = mime_parser.parts.iter().all(|part| part.is_reaction);
     let mut parts = mime_parser.parts.iter().peekable();
     while let Some(part) = parts.next() {

src/sync.rs

@@ -71,6 +71,9 @@ pub(crate) enum SyncData {
     DeleteMessages {
         msgs: Vec<String>, // RFC724 id (i.e. "Message-Id" header)
     },
+    RejectIncomingCall {
+        msg: String, // RFC724 id (i.e. "Message-Id" header)
+    },
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -264,6 +267,7 @@ impl Context {
                     SyncData::Config { key, val } => self.sync_config(key, val).await,
                     SyncData::SaveMessage { src, dest } => self.save_message(src, dest).await,
                     SyncData::DeleteMessages { msgs } => self.sync_message_deletion(msgs).await,
+                    SyncData::RejectIncomingCall { msg } => self.sync_call_rejection(msg).await,
                 },
                 SyncDataOrUnknown::Unknown(data) => {
                     warn!(self, "Ignored unknown sync item: {data}.");