diff --git a/lib/endpoint.js b/lib/endpoint.js
index 5452697..866dc68 100644
--- a/lib/endpoint.js
+++ b/lib/endpoint.js
@@ -902,7 +902,10 @@ class Endpoint extends EventEmitter {
     if (flags.moderator) data.moderator = true;
     if (flags.endconf) data.endConf = true;
     if (flags.mute) data.startMuted = true;
-    // flags['dist-dtmf'] (distribute DTMF to the room) is Phase 2.
+    // flags['dist-dtmf']: this member's DTMF is regenerated as RFC 2833 on
+    // every other member's leg (mod_conference dist-dtmf semantics — the flag
+    // is on the sender, recipients need nothing).
+    if (flags['dist-dtmf']) data.distDtmf = true;
     const res = await this._request('room.join', data);
     this._roomName = conf;
     this._roomMemberId = res.memberId;
diff --git a/test/conference.test.js b/test/conference.test.js
index c60d4dc..bbb3ce5 100644
--- a/test/conference.test.js
+++ b/test/conference.test.js
@@ -34,6 +34,24 @@ test('join sends room.join with mapped flags and returns fsmrf shape', async ()
   assert.deepStrictEqual(res, { memberId: '7', confUuid: 'u-1' });
 });
 
+test("join maps flags['dist-dtmf'] to distDtmf", async () => {
+  const { ep, calls } = makeEp((cmd) =>
+    cmd === 'room.join' ? { roomUuid: 'u-2', memberId: 3 } : {});
+  await ep.join('myconf', { flags: { 'dist-dtmf': true } });
+
+  const join = calls.find((c) => c.cmd === 'room.join');
+  assert.deepStrictEqual(join.data, { room: 'myconf', distDtmf: true });
+});
+
+test('join omits distDtmf when dist-dtmf is not set', async () => {
+  const { ep, calls } = makeEp((cmd) =>
+    cmd === 'room.join' ? { roomUuid: 'u-3', memberId: 4 } : {});
+  await ep.join('myconf', { flags: { moderator: true } });
+
+  const join = calls.find((c) => c.cmd === 'room.join');
+  assert.ok(!('distDtmf' in join.data), 'distDtmf must be absent when the flag is off');
+});
+
 test('api conference get count returns the count as a body string', async () => {
   const { ep } = makeEp((cmd) => (cmd === 'room.query' ? { found: true, count: 3 } : {}));
   const res = await ep.api('conference', ['myconf', 'get', 'count']);