diff --git a/src/IConfigOptions.ts b/src/IConfigOptions.ts
index 9739cc8870..d8c26909df 100644
--- a/src/IConfigOptions.ts
+++ b/src/IConfigOptions.ts
@@ -117,9 +117,9 @@ export interface IConfigOptions {
         obey_asserted_identity?: boolean; // MSC3086
     };
     element_call: {
-        url: string;
-        use_exclusively: boolean;
-        brand: string;
+        url?: string;
+        use_exclusively?: boolean;
+        brand?: string;
     };
 
     logout_redirect_url?: string;
diff --git a/src/components/views/rooms/RoomHeader.tsx b/src/components/views/rooms/RoomHeader.tsx
index 6f0eac864f..013a992698 100644
--- a/src/components/views/rooms/RoomHeader.tsx
+++ b/src/components/views/rooms/RoomHeader.tsx
@@ -52,7 +52,7 @@ import { UPDATE_EVENT } from "../../../stores/AsyncStore";
 import { isVideoRoom as calcIsVideoRoom } from "../../../utils/video-rooms";
 import LegacyCallHandler, { LegacyCallHandlerEvent } from "../../../LegacyCallHandler";
 import { useFeatureEnabled, useSettingValue } from "../../../hooks/useSettings";
-import SdkConfig from "../../../SdkConfig";
+import SdkConfig, { DEFAULTS } from "../../../SdkConfig";
 import { useEventEmitterState, useTypedEventEmitterState } from "../../../hooks/useEventEmitter";
 import { useWidgets } from "../right_panel/RoomSummaryCard";
 import { WidgetType } from "../../../widgets/WidgetType";
@@ -195,7 +195,7 @@ const VideoCallButton: FC<VideoCallButtonProps> = ({ room, busy, setBusy, behavi
     let menu: JSX.Element | null = null;
     if (menuOpen) {
         const buttonRect = buttonRef.current!.getBoundingClientRect();
-        const brand = SdkConfig.get("element_call").brand;
+        const brand = SdkConfig.get("element_call").brand ?? DEFAULTS.element_call.brand;
         menu = <IconizedContextMenu {...aboveLeftOf(buttonRect)} onFinished={closeMenu}>
             <IconizedContextMenuOptionList>
                 <IconizedContextMenuOption label={_t("Video call (Jitsi)")} onClick={onJitsiClick} />
@@ -230,7 +230,9 @@ const CallButtons: FC<CallButtonsProps> = ({ room }) => {
     const groupCallsEnabled = useFeatureEnabled("feature_group_calls");
     const videoRoomsEnabled = useFeatureEnabled("feature_video_rooms");
     const isVideoRoom = useMemo(() => videoRoomsEnabled && calcIsVideoRoom(room), [videoRoomsEnabled, room]);
-    const useElementCallExclusively = useMemo(() => SdkConfig.get("element_call").use_exclusively, []);
+    const useElementCallExclusively = useMemo(() => {
+        return SdkConfig.get("element_call").use_exclusively ?? DEFAULTS.element_call.use_exclusively;
+    }, []);
 
     const hasLegacyCall = useEventEmitterState(
         LegacyCallHandler.instance,
diff --git a/src/components/views/settings/tabs/room/RolesRoomSettingsTab.tsx b/src/components/views/settings/tabs/room/RolesRoomSettingsTab.tsx
index 1c70c3ea39..5da3996154 100644
--- a/src/components/views/settings/tabs/room/RolesRoomSettingsTab.tsx
+++ b/src/components/views/settings/tabs/room/RolesRoomSettingsTab.tsx
@@ -32,7 +32,7 @@ import SettingsFieldset from '../../SettingsFieldset';
 import SettingsStore from "../../../../../settings/SettingsStore";
 import { VoiceBroadcastInfoEventType } from '../../../../../voice-broadcast';
 import { ElementCall } from "../../../../../models/Call";
-import SdkConfig from "../../../../../SdkConfig";
+import SdkConfig, { DEFAULTS } from "../../../../../SdkConfig";
 
 interface IEventShowOpts {
     isState?: boolean;
@@ -446,7 +446,7 @@ export default class RolesRoomSettingsTab extends React.Component<IProps> {
 
             let label = plEventsToLabels[eventType];
             if (label) {
-                const brand = SdkConfig.get("element_call").brand;
+                const brand = SdkConfig.get("element_call").brand ?? DEFAULTS.element_call.brand;
                 label = _t(label, { brand });
             } else {
                 label = _t("Send %(eventType)s events", { eventType });
diff --git a/src/components/views/settings/tabs/room/VoipRoomSettingsTab.tsx b/src/components/views/settings/tabs/room/VoipRoomSettingsTab.tsx
index 29863b64aa..b8dca6205c 100644
--- a/src/components/views/settings/tabs/room/VoipRoomSettingsTab.tsx
+++ b/src/components/views/settings/tabs/room/VoipRoomSettingsTab.tsx
@@ -25,7 +25,7 @@ import SettingsSubsection from "../../shared/SettingsSubsection";
 import SettingsTab from "../SettingsTab";
 import { ElementCall } from "../../../../../models/Call";
 import { useRoomState } from "../../../../../hooks/useRoomState";
-import SdkConfig from "../../../../../SdkConfig";
+import SdkConfig, { DEFAULTS } from "../../../../../SdkConfig";
 
 interface ElementCallSwitchProps {
     roomId: string;
@@ -69,7 +69,7 @@ const ElementCallSwitch: React.FC<ElementCallSwitchProps> = ({ roomId }) => {
         });
     }, [roomId, content, events, isPublic]);
 
-    const brand = SdkConfig.get("element_call").brand;
+    const brand = SdkConfig.get("element_call").brand ?? DEFAULTS.element_call.brand;
 
     return <LabelledToggleSwitch
         data-testid="element-call-switch"
diff --git a/src/models/Call.ts b/src/models/Call.ts
index c12c4fdfc9..455b08e6a5 100644
--- a/src/models/Call.ts
+++ b/src/models/Call.ts
@@ -31,7 +31,7 @@ import type { Room } from "matrix-js-sdk/src/models/room";
 import type { RoomMember } from "matrix-js-sdk/src/models/room-member";
 import type { ClientWidgetApi } from "matrix-widget-api";
 import type { IApp } from "../stores/WidgetStore";
-import SdkConfig from "../SdkConfig";
+import SdkConfig, { DEFAULTS } from "../SdkConfig";
 import SettingsStore from "../settings/SettingsStore";
 import MediaDeviceHandler, { MediaDeviceKindEnum } from "../MediaDeviceHandler";
 import { timeout } from "../utils/promise";
@@ -622,7 +622,7 @@ export class ElementCall extends Call {
 
     private constructor(public readonly groupCall: MatrixEvent, client: MatrixClient) {
         // Splice together the Element Call URL for this call
-        const url = new URL(SdkConfig.get("element_call").url);
+        const url = new URL(SdkConfig.get("element_call").url ?? DEFAULTS.element_call.url);
         url.pathname = "/room";
         const params = new URLSearchParams({
             embed: "",
diff --git a/src/stores/widgets/StopGapWidgetDriver.ts b/src/stores/widgets/StopGapWidgetDriver.ts
index 9de442a4b9..dd806dd6dd 100644
--- a/src/stores/widgets/StopGapWidgetDriver.ts
+++ b/src/stores/widgets/StopGapWidgetDriver.ts
@@ -40,7 +40,7 @@ import { logger } from "matrix-js-sdk/src/logger";
 import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
 import { Direction } from "matrix-js-sdk/src/matrix";
 
-import SdkConfig from "../../SdkConfig";
+import SdkConfig, { DEFAULTS } from "../../SdkConfig";
 import { iterableDiff, iterableIntersection } from "../../utils/iterables";
 import { MatrixClientPeg } from "../../MatrixClientPeg";
 import Modal from "../../Modal";
@@ -104,7 +104,10 @@ export class StopGapWidgetDriver extends WidgetDriver {
             // Auto-approve the legacy visibility capability. We send it regardless of capability.
             // Widgets don't technically need to request this capability, but Scalar still does.
             this.allowedCapabilities.add("visibility");
-        } else if (virtual && new URL(SdkConfig.get("element_call").url).origin === this.forWidget.origin) {
+        } else if (
+            virtual
+            && new URL(SdkConfig.get("element_call").url ?? DEFAULTS.element_call.url).origin === this.forWidget.origin
+        ) {
             // This is a trusted Element Call widget that we control
             this.allowedCapabilities.add(MatrixCapabilities.AlwaysOnScreen);
             this.allowedCapabilities.add(MatrixCapabilities.MSC3846TurnServers);