diff --git a/src/CallHandler.js b/src/CallHandler.js
index 1ac93a8063..2f931d8e3f 100644
--- a/src/CallHandler.js
+++ b/src/CallHandler.js
@@ -264,6 +264,18 @@ function _onAction(payload) {
                     description: "You cannot place VoIP calls in this browser."
                 });
             }
+            else if (MatrixClientPeg.get().isRoomEncrypted(payload.room_id)) {
+                // Conference calls are implemented by sending the media to central
+                // server which combines the audio from all the participants together
+                // into a single stream. This is incompatible with end-to-end encryption
+                // because a central server would be decrypting the audio for each
+                // participant.
+                // Therefore we disable conference calling in E2E rooms.
+                const ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
+                Modal.createDialog(ErrorDialog, {
+                    description: "Conference calls are not supported in encrypted rooms",
+                });
+            }
             else {
                 var QuestionDialog = sdk.getComponent("dialogs.QuestionDialog");
                 Modal.createDialog(QuestionDialog, {