Support 'answered elsewhere'

Show a dialog for now, telling the user someone beat them to it.

Only useful with matrix-org/matrix-js-sdk#1522
(but can be merged safely without).

Author: dbkr

src/CallHandler.tsx

@@ -262,6 +262,12 @@ export default class CallHandler {
                         Modal.createTrackedDialog('Call Handler', 'Call Failed', ErrorDialog, {
                             title, description,
                         });
+                    } else if (call.hangupReason === CallErrorCode.AnsweredElsewhere) {
+                        this.play(AudioID.Busy);
+                        Modal.createTrackedDialog('Call Handler', 'Call Failed', ErrorDialog, {
+                            title: _t("Answered Elsewhere"),
+                            description: _t("The call was answered on another device."),
+                        });
                     } else {
                         this.play(AudioID.CallEnd);
                     }

src/i18n/strings/en_EN.json

@@ -39,6 +39,8 @@
     "The other party declined the call.": "The other party declined the call.",
     "The remote side failed to pick up": "The remote side failed to pick up",
     "The call could not be established": "The call could not be established",
+    "Answered Elsewhere": "Answered Elsewhere",
+    "The call was answered on another device.": "The call was answered on another device.",
     "Call failed due to misconfigured server": "Call failed due to misconfigured server",
     "Please ask the administrator of your homeserver (<code>%(homeserverDomain)s</code>) to configure a TURN server in order for calls to work reliably.": "Please ask the administrator of your homeserver (<code>%(homeserverDomain)s</code>) to configure a TURN server in order for calls to work reliably.",
     "Alternatively, you can try to use the public server at <code>turn.matrix.org</code>, but this will not be as reliable, and it will share your IP address with that server. You can also manage this in Settings.": "Alternatively, you can try to use the public server at <code>turn.matrix.org</code>, but this will not be as reliable, and it will share your IP address with that server. You can also manage this in Settings.",