diff --git a/webclient/components/matrix/matrix-call.js b/webclient/components/matrix/matrix-call.js
index 494a37f34..a025ccf63 100644
--- a/webclient/components/matrix/matrix-call.js
+++ b/webclient/components/matrix/matrix-call.js
@@ -42,11 +42,13 @@ window.RTCIceCandidate = window.RTCIceCandidate || window.webkitRTCIceCandidate
 
 // Returns true if the browser supports all required features to make WebRTC call
 var isWebRTCSupported = function () {
-    return (navigator.getUserMedia || window.RTCPeerConnection || window.RTCSessionDescription || window.RTCIceCandidate);
+    return !!(navigator.getUserMedia || window.RTCPeerConnection || window.RTCSessionDescription || window.RTCIceCandidate);
 };
 
 angular.module('MatrixCall', [])
 .factory('MatrixCall', ['matrixService', 'matrixPhoneService', '$rootScope', '$timeout', function MatrixCallFactory(matrixService, matrixPhoneService, $rootScope, $timeout) {
+    $rootScope.isWebRTCSupported = isWebRTCSupported();
+
     var MatrixCall = function(room_id) {
         this.room_id = room_id;
         this.call_id = "c" + new Date().getTime();
diff --git a/webclient/components/matrix/matrix-phone-service.js b/webclient/components/matrix/matrix-phone-service.js
index d05eecf72..9d0b84fb2 100644
--- a/webclient/components/matrix/matrix-phone-service.js
+++ b/webclient/components/matrix/matrix-phone-service.js
@@ -59,6 +59,16 @@ angular.module('matrixPhoneService', [])
 
             var MatrixCall = $injector.get('MatrixCall');
             var call = new MatrixCall(event.room_id);
+
+            if (!isWebRTCSupported()) {
+                console.log("Incoming call ID "+msg.call_id+" but this browser doesn't support WebRTC");
+                // don't hang up the call: there could be other clients connected that do support WebRTC and declining the
+                // the call on their behalf would be really annoying.
+                // instead, we broadcast a fake call event with a non-functional call object
+                $rootScope.$broadcast(matrixPhoneService.INCOMING_CALL_EVENT, call);
+                return;
+            }
+
             call.call_id = msg.call_id;
             call.initWithInvite(event);
             matrixPhoneService.allCalls[call.call_id] = call;
diff --git a/webclient/index.html b/webclient/index.html
index 47d3ebf65..39174d679 100644
--- a/webclient/index.html
+++ b/webclient/index.html
@@ -79,7 +79,7 @@
                     </span>
                 </div>
                 <span ng-show="currentCall.state == 'ringing'">
-                    <button ng-click="answerCall()">Answer {{ currentCall.type }} call</button>
+                    <button ng-click="answerCall()" ng-disabled="!isWebRTCSupported" title="{{isWebRTCSupported ? '' : 'Your browser does not support VoIP' }}">Answer {{ currentCall.type }} call</button>
                     <button ng-click="hangupCall()">Reject</button>
                 </span>
                 <button ng-click="hangupCall()" ng-show="currentCall && currentCall.state != 'ringing' && currentCall.state != 'ended' && currentCall.state != 'fledgling'">Hang up</button>
diff --git a/webclient/room/room-controller.js b/webclient/room/room-controller.js
index 7f2d40512..166434d1a 100644
--- a/webclient/room/room-controller.js
+++ b/webclient/room/room-controller.js
@@ -34,7 +34,6 @@ angular.module('RoomController', ['ngSanitize', 'matrixFilter', 'mFileInput'])
         stream_failure: undefined, // the response when the stream fails
         waiting_for_joined_event: false,  // true when the join request is pending. Back to false once the corresponding m.room.member event is received
         messages_visibility: "hidden", // In order to avoid flickering when scrolling down the message table at the page opening, delay the message table display
-        webRTCSupported: isWebRTCSupported() // true if the browser does not support WebRTC
     };
     $scope.members = {};
     $scope.autoCompleting = false;
diff --git a/webclient/room/room.html b/webclient/room/room.html
index dfbea492d..d12f79cd2 100644
--- a/webclient/room/room.html
+++ b/webclient/room/room.html
@@ -111,8 +111,8 @@
                               ng-class="containsBingWord(msg.content.body) && msg.user_id != state.user_id ? msg.echo_msg_state + ' messageBing' : msg.echo_msg_state"
                               ng-bind-html="((msg.content.msgtype === 'm.text') ? msg.content.body : '') | linky:'_blank'"/>
 
-                        <span ng-show='msg.type === "m.call.invite" && msg.user_id == state.user_id'>Outgoing Call</span>
-                        <span ng-show='msg.type === "m.call.invite" && msg.user_id != state.user_id'>Incoming Call</span>
+                        <span ng-show='msg.type === "m.call.invite" && msg.user_id == state.user_id'>Outgoing Call{{ isWebRTCSupported ? '' : ' (But your browser does not support VoIP)' }}</span>
+                        <span ng-show='msg.type === "m.call.invite" && msg.user_id != state.user_id'>Incoming Call{{ isWebRTCSupported ? '' : ' (But your browser does not support VoIP)' }}</span>
 
                         <div ng-show='msg.content.msgtype === "m.image"'>
                             <div ng-hide='msg.content.thumbnail_url' ng-style="msg.content.body.h && { 'height' : (msg.content.body.h < 320) ? msg.content.body.h : 320}">
@@ -178,15 +178,15 @@
                 <button ng-click="leaveRoom()" ng-disabled="state.permission_denied">Leave</button>
                 <button ng-click="startVoiceCall()"
                         ng-show="(currentCall == undefined || currentCall.state == 'ended')"
-                        ng-disabled="state.permission_denied || !state.webRTCSupported || memberCount() != 2"
-                        title ="{{ !state.webRTCSupported ? 'VoIP requires webRTC but your browser does not support it' : (memberCount() == 2 ? '' : 'VoIP calls can only be made in rooms with two participants') }}"
+                        ng-disabled="state.permission_denied || !isWebRTCSupported || memberCount() != 2"
+                        title ="{{ !isWebRTCSupported ? 'VoIP requires webRTC but your browser does not support it' : (memberCount() == 2 ? '' : 'VoIP calls can only be made in rooms with two participants') }}"
                         >
                     Voice Call
                 </button>
                 <button ng-click="startVideoCall()"
                         ng-show="(currentCall == undefined || currentCall.state == 'ended')"
-                        ng-disabled="state.permission_denied || !state.webRTCSupported || memberCount() != 2"
-                        title ="{{ !state.webRTCSupported ? 'VoIP requires webRTC but your browser does not support it' : (memberCount() == 2 ? '' : 'VoIP calls can only be made in rooms with two participants') }}"
+                        ng-disabled="state.permission_denied || !isWebRTCSupported || memberCount() != 2"
+                        title ="{{ !isWebRTCSupported ? 'VoIP requires webRTC but your browser does not support it' : (memberCount() == 2 ? '' : 'VoIP calls can only be made in rooms with two participants') }}"
                         >
                     Video Call
                 </button>