diff --git a/src/domain/session/room/timeline/tiles/CallTile.js b/src/domain/session/room/timeline/tiles/CallTile.js
index ffb9ef59..05762bc0 100644
--- a/src/domain/session/room/timeline/tiles/CallTile.js
+++ b/src/domain/session/room/timeline/tiles/CallTile.js
@@ -94,7 +94,7 @@ export class CallTile extends SimpleTile {
     }
 
     get canJoin() {
-        return this._call && !this._call.hasJoined;
+        return this._call && !this._call.hasJoined && !this._call.usesFoci;
     }
 
     get canLeave() {
@@ -118,11 +118,14 @@ export class CallTile extends SimpleTile {
     }
 
     get typeLabel() {
+        if (this._call && this._call.usesFoci) {
+            return `This call uses a stream-forwarding unit, which isn't supported yet, so you can't join this call.`;
+        }
         if (this.type === CallType.Video) {
-                return `Video call`;
-            } else {
-                return `Voice call`;
-            }
+            return `Video call`;
+        } else {
+            return `Voice call`;
+        }
     }
 
     get type() {
diff --git a/src/domain/session/toast/ToastCollectionViewModel.ts b/src/domain/session/toast/ToastCollectionViewModel.ts
index 18b58b76..709f5b81 100644
--- a/src/domain/session/toast/ToastCollectionViewModel.ts
+++ b/src/domain/session/toast/ToastCollectionViewModel.ts
@@ -79,7 +79,7 @@ export class ToastCollectionViewModel extends ViewModel<SegmentType, Options> {
     
     private _shouldShowNotification(call: GroupCall): boolean {
         const currentlyOpenedRoomId = this.navigation.path.get("room")?.value;
-        if (!call.isLoadedFromStorage && call.roomId !== currentlyOpenedRoomId) {
+        if (!call.isLoadedFromStorage && call.roomId !== currentlyOpenedRoomId && !call.usesFoci) {
             return true;
         }
         return false;
diff --git a/src/matrix/calls/callEventTypes.ts b/src/matrix/calls/callEventTypes.ts
index a0eb986c..879d0c11 100644
--- a/src/matrix/calls/callEventTypes.ts
+++ b/src/matrix/calls/callEventTypes.ts
@@ -22,11 +22,17 @@ export enum EventType {
 // TODO: Change to "sdp_stream_metadata" when MSC3077 is merged
 export const SDPStreamMetadataKey = "org.matrix.msc3077.sdp_stream_metadata";
 
+export interface FocusConfig {
+    user_id: string,
+    device_id: string
+}
+
 export interface CallDeviceMembership {
     device_id: string,
     session_id: string,
     ["expires_ts"]?: number,
     feeds?: Array<{purpose: string}>
+    ["m.foci.active"]?: Array<FocusConfig>
 }
 
 export interface CallMembership {
diff --git a/src/matrix/calls/group/GroupCall.ts b/src/matrix/calls/group/GroupCall.ts
index e0099f4e..0460c212 100644
--- a/src/matrix/calls/group/GroupCall.ts
+++ b/src/matrix/calls/group/GroupCall.ts
@@ -145,6 +145,15 @@ export class GroupCall extends EventEmitter<{change: never}> {
         return !!this.callContent?.["m.terminated"];
     }
 
+    get usesFoci(): boolean {
+        for (const member of this._members.values()) {
+            if (member.usesFoci) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     get duration(): number | undefined {
         if (typeof this.startTime === "number") {
             return (this.options.clock.now() - this.startTime);
@@ -181,7 +190,8 @@ export class GroupCall extends EventEmitter<{change: never}> {
 
     join(localMedia: LocalMedia, log?: ILogItem): Promise<void> {
         return this.options.logger.wrapOrRun(log, "Call.join", async joinLog => {
-            if (this._state !== GroupCallState.Created || this.joinedData) {
+            if (this._state !== GroupCallState.Created || this.joinedData || this.usesFoci) {
+                localMedia.dispose();
                 return;
             }
             const logItem = this.options.logger.child({
@@ -217,7 +227,7 @@ export class GroupCall extends EventEmitter<{change: never}> {
                     this.emitChange();
                 });
                 // send invite to all members that are < my userId
-                for (const [,member] of this._members) {
+                for (const member of this._members.values()) {
                     this.connectToMember(member, joinedData, log);
                 }
             });
@@ -521,7 +531,7 @@ export class GroupCall extends EventEmitter<{change: never}> {
     disconnect(log: ILogItem): boolean {
         return this.errorBoundary.try(() => {
             if (this.hasJoined) {
-                for (const [,member] of this._members) {
+                for (const member of this._members.values()) {
                     const disconnectLogItem = member.disconnect(true);
                     if (disconnectLogItem) {
                         log.refDetached(disconnectLogItem);
diff --git a/src/matrix/calls/group/Member.ts b/src/matrix/calls/group/Member.ts
index e097804c..ab99c6b8 100644
--- a/src/matrix/calls/group/Member.ts
+++ b/src/matrix/calls/group/Member.ts
@@ -117,6 +117,11 @@ export class Member {
         return this.errorBoundary.error;
     }
 
+    get usesFoci(): boolean {
+        const activeFoci = this.callDeviceMembership["m.foci.active"];
+        return Array.isArray(activeFoci) && activeFoci.length > 0;
+    }
+
     private _renewExpireTimeout(log: ILogItem) {
         this.expireTimeout?.dispose();
         this.expireTimeout = undefined;