diff --git a/spec/unit/matrixrtc/types.spec.ts b/spec/unit/matrixrtc/types.spec.ts
new file mode 100644
index 0000000000..2fb572e7a9
--- /dev/null
+++ b/spec/unit/matrixrtc/types.spec.ts
@@ -0,0 +1,135 @@
+/*
+Copyright 2025 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { type CallMembership } from "../../../src/matrixrtc";
+import { isMyMembership, parseCallNotificationContent } from "../../../src/matrixrtc/types";
+
+describe("types", () => {
+    describe("isMyMembership", () => {
+        it("returns false if userId is different", () => {
+            expect(
+                isMyMembership(
+                    { sender: "@alice:example.org", deviceId: "DEVICE" } as CallMembership,
+                    "@bob:example.org",
+                    "DEVICE",
+                ),
+            ).toBe(false);
+        });
+        it("returns true if userId and device is the same", () => {
+            expect(
+                isMyMembership(
+                    { sender: "@alice:example.org", deviceId: "DEVICE" } as CallMembership,
+                    "@alice:example.org",
+                    "DEVICE",
+                ),
+            ).toBe(true);
+        });
+    });
+});
+
+describe("IRTCNotificationContent", () => {
+    const validBase = Object.freeze({
+        "m.mentions": { user_ids: [], room: true },
+        "notification_type": "notification",
+        "sender_ts": 123,
+        "lifetime": 1000,
+    });
+
+    it("parses valid content", () => {
+        const res = parseCallNotificationContent({ ...validBase });
+        expect(res).toMatchObject(validBase);
+    });
+
+    it("caps lifetime to 120000ms", () => {
+        const res = parseCallNotificationContent({ ...validBase, lifetime: 130000 });
+        expect(res.lifetime).toBe(120000);
+    });
+
+    it("throws on malformed m.mentions", () => {
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                "m.mentions": "not an object",
+            } as any),
+        ).toThrow("malformed m.mentions");
+    });
+
+    it("throws on missing or invalid notification_type", () => {
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                notification_type: undefined,
+            } as any),
+        ).toThrow("Missing or invalid notification_type");
+
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                notification_type: 123 as any,
+            } as any),
+        ).toThrow("Missing or invalid notification_type");
+    });
+
+    it("throws on missing or invalid sender_ts", () => {
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                sender_ts: undefined,
+            } as any),
+        ).toThrow("Missing or invalid sender_ts");
+
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                sender_ts: "123" as any,
+            } as any),
+        ).toThrow("Missing or invalid sender_ts");
+    });
+
+    it("throws on missing or invalid lifetime", () => {
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                lifetime: undefined,
+            } as any),
+        ).toThrow("Missing or invalid lifetime");
+
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                lifetime: "1000" as any,
+            } as any),
+        ).toThrow("Missing or invalid lifetime");
+    });
+
+    it("accepts valid relation (m.reference)", () => {
+        // Note: parseCallNotificationContent currently checks `relation.rel_type` rather than `m.relates_to`.
+        const res = parseCallNotificationContent({
+            ...validBase,
+            relation: { rel_type: "m.reference", event_id: "$ev" },
+        } as any);
+        expect(res).toBeTruthy();
+    });
+
+    it("throws on invalid relation rel_type", () => {
+        expect(() =>
+            parseCallNotificationContent({
+                ...validBase,
+                relation: { rel_type: "m.annotation", event_id: "$ev" },
+            } as any),
+        ).toThrow("Invalid relation");
+    });
+});
diff --git a/src/matrixrtc/types.ts b/src/matrixrtc/types.ts
index b344a22d8b..98d057b25a 100644
--- a/src/matrixrtc/types.ts
+++ b/src/matrixrtc/types.ts
@@ -13,7 +13,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-import type { IMentions } from "../matrix.ts";
+import type { IContent, IMentions } from "../matrix.ts";
 import type { RelationEvent } from "../types.ts";
 import type { CallMembership } from "./CallMembership.ts";
 
@@ -102,9 +102,45 @@ export type RTCNotificationType = "ring" | "notification";
  * May be any string, although `"audio"` and `"video"` are commonly accepted values.
  */
 export type RTCCallIntent = "audio" | "video" | string;
+
+/**
+ * This will check if the content has all the expected fields to be a valid IRTCNotificationContent.
+ * It will also cap the lifetime to 120000ms if a higher value is provided.
+ * @param content
+ * @throws if the content is invalid
+ * @returns a parsed IRTCNotificationContent
+ */
+export function parseCallNotificationContent(content: IContent): IRTCNotificationContent {
+    if (content["m.mentions"] && typeof content["m.mentions"] !== "object") {
+        throw new Error("malformed m.mentions");
+    }
+    if (typeof content["notification_type"] !== "string") {
+        throw new Error("Missing or invalid notification_type");
+    }
+    if (typeof content["sender_ts"] !== "number") {
+        throw new Error("Missing or invalid sender_ts");
+    }
+    if (typeof content["lifetime"] !== "number") {
+        throw new Error("Missing or invalid lifetime");
+    }
+
+    if (content["relation"] && content["relation"]["rel_type"] !== "m.reference") {
+        throw new Error("Invalid relation");
+    }
+    if (content["m.call.intent"] && typeof content["m.call.intent"] !== "string") {
+        throw new Error("Invalid m.call.intent");
+    }
+
+    const cappedLifetime = content["lifetime"] >= 120000 ? 120000 : content["lifetime"];
+    return { ...content, lifetime: cappedLifetime } as IRTCNotificationContent;
+}
+
+/**
+ * Interface for `org.matrix.msc4075.rtc.notification` events.
+ * Don't cast event content to this directly. Use `parseCallNotificationContent` instead to validate the content first.
+ */
 export interface IRTCNotificationContent extends RelationEvent {
-    "m.mentions": IMentions;
-    "decline_reason"?: string;
+    "m.mentions"?: IMentions;
     "notification_type": RTCNotificationType;
     /**
      * The initial intent of the calling user.