diff --git a/spec/test-utils/webrtc.ts b/spec/test-utils/webrtc.ts
index 9ed142fcc00..80ccbef2668 100644
--- a/spec/test-utils/webrtc.ts
+++ b/spec/test-utils/webrtc.ts
@@ -109,6 +109,12 @@ export class MockRTCPeerConnection {
             sdp: DUMMY_SDP,
         });
     }
+    createAnswer() {
+        return Promise.resolve({
+            type: 'answer',
+            sdp: DUMMY_SDP,
+        });
+    }
     setRemoteDescription() {
         return Promise.resolve();
     }
diff --git a/spec/unit/webrtc/call.spec.ts b/spec/unit/webrtc/call.spec.ts
index 338e968b190..1cedd5c7cc4 100644
--- a/spec/unit/webrtc/call.spec.ts
+++ b/spec/unit/webrtc/call.spec.ts
@@ -25,7 +25,9 @@ import {
     installWebRTCMocks,
 } from "../../test-utils/webrtc";
 import { CallFeed } from "../../../src/webrtc/callFeed";
-import { EventType } from "../../../src";
+import { EventType, MatrixEvent } from "../../../src";
+
+const FAKE_ROOM_ID = "!foo:bar";
 
 const startVoiceCall = async (client: TestClient, call: MatrixCall): Promise<void> => {
     const callPromise = call.placeVoiceCall();
@@ -43,6 +45,31 @@ const startVideoCall = async (client: TestClient, call: MatrixCall): Promise<voi
     call.getOpponentMember = jest.fn().mockReturnValue({ userId: "@bob:bar.uk" });
 };
 
+const fakeIncomingCall = async (client: TestClient, call: MatrixCall, version: string | number = "1") => {
+    const callPromise = call.initWithInvite({
+        getContent: jest.fn().mockReturnValue({
+            version,
+            call_id: "call_id",
+            party_id: "remote_party_id",
+            offer: {
+                sdp: DUMMY_SDP,
+            },
+        }),
+        getSender: () => "@test:foo",
+        getLocalAge: () => null,
+    } as unknown as MatrixEvent);
+    call.getFeeds().push(new CallFeed({
+        client: client.client,
+        userId: "remote_user_id",
+        // @ts-ignore Mock
+        stream: new MockMediaStream("remote_stream_id", [new MockMediaStreamTrack("remote_tack_id")]),
+        id: "remote_feed_id",
+        purpose: SDPStreamMetadataPurpose.Usermedia,
+    }));
+    await client.httpBackend.flush("");
+    await callPromise;
+};
+
 describe('Call', function() {
     let client;
     let call;
@@ -60,7 +87,7 @@ describe('Call', function() {
         client = new TestClient("@alice:foo", "somedevice", "token", undefined, {});
         // We just stub out sendEvent: we're not interested in testing the client's
         // event sending code here
-        client.client.sendEvent = () => {};
+        client.client.sendEvent = jest.fn();
         client.client.mediaHandler = new MockMediaHandler;
         client.client.getMediaHandler = () => client.client.mediaHandler;
         client.httpBackend.when("GET", "/voip/turnServer").respond(200, {});
@@ -74,7 +101,7 @@ describe('Call', function() {
 
         call = new MatrixCall({
             client: client.client,
-            roomId: '!foo:bar',
+            roomId: FAKE_ROOM_ID,
         });
         // call checks one of these is wired up
         call.on('error', () => {});
@@ -594,28 +621,7 @@ describe('Call', function() {
     });
 
     it("should end call after receiving a select event with a different party id", async () => {
-        const callPromise = call.initWithInvite({
-            getContent: () => ({
-                version: 1,
-                call_id: "call_id",
-                party_id: "remote_party_id",
-                offer: {
-                    sdp: DUMMY_SDP,
-                },
-            }),
-            getSender: () => "@test:foo",
-            getLocalAge: () => null,
-        });
-        call.feeds.push(new CallFeed({
-            client,
-            userId: "remote_user_id",
-            // @ts-ignore Mock
-            stream: new MockMediaStream("remote_stream_id", [new MockMediaStreamTrack("remote_tack_id")]),
-            id: "remote_feed_id",
-            purpose: SDPStreamMetadataPurpose.Usermedia,
-        }));
-        await client.httpBackend.flush();
-        await callPromise;
+        await fakeIncomingCall(client, call);
 
         const callHangupCallback = jest.fn();
         call.on(CallEvent.Hangup, callHangupCallback);
@@ -845,4 +851,72 @@ describe('Call', function() {
             });
         });
     });
+
+    describe("rejecting calls", () => {
+        it("sends hangup event when rejecting v0 calls", async () => {
+            await fakeIncomingCall(client, call, 0);
+
+            call.reject();
+
+            expect(client.client.sendEvent).toHaveBeenCalledWith(
+                FAKE_ROOM_ID,
+                EventType.CallHangup,
+                expect.objectContaining({
+                    call_id: call.callId,
+                }),
+            );
+        });
+
+        it("sends reject event when rejecting v1 calls", async () => {
+            await fakeIncomingCall(client, call, "1");
+
+            call.reject();
+
+            expect(client.client.sendEvent).toHaveBeenCalledWith(
+                FAKE_ROOM_ID,
+                EventType.CallReject,
+                expect.objectContaining({
+                    call_id: call.callId,
+                }),
+            );
+        });
+
+        it("does not reject a call that has already been answered", async () => {
+            await fakeIncomingCall(client, call, "1");
+
+            await call.answer();
+
+            client.client.sendEvent.mockReset();
+
+            let caught = false;
+            try {
+                call.reject();
+            } catch (e) {
+                caught = true;
+            }
+
+            expect(caught).toEqual(true);
+            expect(client.client.sendEvent).not.toHaveBeenCalled();
+
+            call.hangup();
+        });
+
+        it("hangs up a call", async () => {
+            await fakeIncomingCall(client, call, "1");
+
+            await call.answer();
+
+            client.client.sendEvent.mockReset();
+
+            call.hangup();
+
+            expect(client.client.sendEvent).toHaveBeenCalledWith(
+                FAKE_ROOM_ID,
+                EventType.CallHangup,
+                expect.objectContaining({
+                    call_id: call.callId,
+                }),
+            );
+        });
+    });
 });
diff --git a/src/webrtc/call.ts b/src/webrtc/call.ts
index 43ef311882f..8e14e06a880 100644
--- a/src/webrtc/call.ts
+++ b/src/webrtc/call.ts
@@ -1569,6 +1569,10 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
 
         try {
             await this.peerConn.setLocalDescription(answer);
+
+            // make sure we're still going
+            if (this.callHasEnded()) return;
+
             this.setState(CallState.Connecting);
 
             // Allow a short time for initial candidates to be gathered
@@ -1576,6 +1580,9 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
                 setTimeout(resolve, 200);
             });
 
+            // make sure the call hasn't ended before we continue
+            if (this.callHasEnded()) return;
+
             this.sendAnswer();
         } catch (err) {
             logger.debug(`Call ${this.callId} Error setting local description!`, err);