diff --git a/extensions/voice-call/src/media-stream.lifecycle.test.ts b/extensions/voice-call/src/media-stream.lifecycle.test.ts
index 62ea111a32cf..a8a6c63553e7 100644
--- a/extensions/voice-call/src/media-stream.lifecycle.test.ts
+++ b/extensions/voice-call/src/media-stream.lifecycle.test.ts
@@ -70,4 +70,62 @@ describe("MediaStreamHandler lifecycle", () => {
       await server.close();
     }
   });
+
+  it("terminates active streams and shares concurrent close completion", async () => {
+    const closeSession = vi.fn();
+    const onConnect = vi.fn();
+    const onDisconnect = vi.fn();
+    const handler = new MediaStreamHandler({
+      transcriptionProvider: {
+        createSession: () => ({
+          connect: async () => {},
+          sendAudio: () => {},
+          close: closeSession,
+          isConnected: () => true,
+        }),
+        id: "openai",
+        label: "OpenAI",
+        isConfigured: () => true,
+      },
+      providerConfig: {},
+      shouldAcceptStream: () => true,
+      onConnect,
+      onDisconnect,
+    });
+    const server = await startUpgradeWsServer({
+      urlPath: "/voice/stream",
+      onUpgrade: (request, socket, head) => {
+        handler.handleUpgrade(request, socket, head);
+      },
+    });
+    const ws = await connectWs(server.url);
+
+    try {
+      ws.send(
+        JSON.stringify({
+          event: "start",
+          streamSid: "MZ-shutdown",
+          start: { callSid: "CA-shutdown" },
+        }),
+      );
+      await vi.waitFor(() => {
+        expect(onConnect).toHaveBeenCalledWith("CA-shutdown", "MZ-shutdown");
+      });
+
+      const closed = waitForClose(ws);
+      const firstClose = handler.close();
+      const secondClose = handler.close();
+
+      expect(secondClose).toBe(firstClose);
+      await firstClose;
+      expect(await closed).toEqual({ code: 1006, reason: "" });
+      expect(closeSession).toHaveBeenCalledTimes(1);
+      expect(onDisconnect).toHaveBeenCalledWith("CA-shutdown", "MZ-shutdown");
+      expect(onDisconnect).toHaveBeenCalledTimes(1);
+    } finally {
+      ws.terminate();
+      await handler.close();
+      await server.close();
+    }
+  });
 });
diff --git a/extensions/voice-call/src/media-stream.ts b/extensions/voice-call/src/media-stream.ts
index b93d811b88c3..07abbbb5c360 100644
--- a/extensions/voice-call/src/media-stream.ts
+++ b/extensions/voice-call/src/media-stream.ts
@@ -138,6 +138,8 @@ function parseTwilioMediaMessage(data: RawData): TwilioMediaMessage {
  */
 export class MediaStreamHandler {
   private wss: WebSocketServer | null = null;
+  private closePromise: Promise<void> | null = null;
+  private closing = false;
   private sessions = new Map<string, StreamSession>();
   private config: MediaStreamConfig;
   /** Pending sockets that have upgraded but not yet sent an accepted `start` frame. */
@@ -172,6 +174,11 @@ export class MediaStreamHandler {
    * Handle WebSocket upgrade for media stream connections.
    */
   handleUpgrade(request: IncomingMessage, socket: Duplex, head: Buffer): void {
+    if (this.closing) {
+      this.rejectUpgrade(socket, 503, "Media stream handler is shutting down");
+      return;
+    }
+
     if (!this.wss) {
       this.wss = new WebSocketServer({
         noServer: true,
@@ -221,6 +228,31 @@ export class MediaStreamHandler {
     }
   }
 
+  close(): Promise<void> {
+    if (this.closePromise) {
+      return this.closePromise;
+    }
+
+    this.closing = true;
+    const wss = this.wss;
+    this.wss = null;
+    this.closePromise = (async () => {
+      if (!wss) {
+        return;
+      }
+      await new Promise<void>((resolve) => {
+        wss.close(() => resolve());
+        for (const ws of wss.clients) {
+          ws.terminate();
+        }
+      });
+    })().finally(() => {
+      this.closing = false;
+      this.closePromise = null;
+    });
+    return this.closePromise;
+  }
+
   /**
    * Handle new WebSocket connection from Twilio.
    */