Don't allow calls when the connection the server has been lost

src/CallHandler.tsx

@@ -54,6 +54,7 @@ import { WidgetLayoutStore, Container } from './stores/widgets/WidgetLayoutStore
 import { getIncomingCallToastKey } from './toasts/IncomingCallToast';
 import ToastStore from './stores/ToastStore';
 import IncomingCallToast from "./toasts/IncomingCallToast";
+import { SyncState } from "matrix-js-sdk/src/sync.api";
 
 export const PROTOCOL_PSTN = 'm.protocol.pstn';
 export const PROTOCOL_PSTN_PREFIXED = 'im.vector.protocol.pstn';
@@ -783,6 +784,14 @@ export default class CallHandler extends EventEmitter {
             return;
         }
 
+        if (MatrixClientPeg.get().getSyncState() === SyncState.Error) {
+            Modal.createTrackedDialog('Call Handler', 'Sync error', ErrorDialog, {
+                title: _t('Connectivity to the server has been lost'),
+                description: _t('You cannot place VoIP calls without a connection to the server.'),
+            });
+            return;
+        }
+
         // don't allow > 2 calls to be placed.
         if (this.getAllActiveCalls().length > 1) {
             Modal.createTrackedDialog('Call Handler', 'Existing Call', ErrorDialog, {

src/i18n/strings/en_EN.json

@@ -56,6 +56,8 @@
     "You're already in a call with this person.": "You're already in a call with this person.",
     "VoIP is unsupported": "VoIP is unsupported",
     "You cannot place VoIP calls in this browser.": "You cannot place VoIP calls in this browser.",
+    "Connectivity to the server has been lost": "Connectivity to the server has been lost",
+    "You cannot place VoIP calls without a connection to the server.": "You cannot place VoIP calls without a connection to the server.",
     "Too Many Calls": "Too Many Calls",
     "You've reached the maximum number of simultaneous calls.": "You've reached the maximum number of simultaneous calls.",
     "You cannot place a call with yourself.": "You cannot place a call with yourself.",