Twilio clone

Exercise SMS OTP, Verify check flows, voice/TwiML callbacks, and conversations in a stateful Twilio twin — magic test numbers, deterministic OTP lookup, and in-memory delivery (no PSTN).

Clone ID: twilio · Binary: clones-twilio · SDK: twilio · Dashboard: Twilio explorer

Start here

Question	Answer
Best for	SMS OTP signup, Verify v2, status callbacks, voice gather flows, and conversation threads
Connect with	`@molar/clones` SDK, Twilio SDK with base URL override, route mode for `api.twilio.com`, REST at clone base URL, or MCP
Known limits	No real carrier delivery; recordings are stub artifacts unless you wire S3 hooks
Seeds	Empty by default; optional JSON seed for phone numbers (see below)

Quick start

import { twilio } from "@molar/clones";

const clone = await twilio.start({ seed: "otp-signup", runId: "run-twilio-01" });

await clone.createMessage({ from: "+15005550006", to: "+14155550123", body: "Hi" });
const verification = await clone.createVerification("+14155550123", "sms");
const code = await clone.lastOTP("+14155550123");
await clone.checkVerification("+14155550123", code);

Advance the virtual clock to move queued messages to delivered.

MCP tools

Tool	Description
`molar_clone_spawn`	Spawn Twilio clone (`kind: "twilio"`, optional `seed`)
`twilio_last_otp`	Read deterministic OTP for a recipient (`adminUrl`, `runId`, `to`)
`molar_clone_advance_clock`	Advance virtual time (scheduled message delivery)
`molar_clone_inject_error`	Inject HTTP errors for rate-limit / 5xx chaos

REST API coverage

Twilio-compatible REST under {base}/t/{runId}/...:

API surface	Operations
Messages	Create SMS/MMS, list, fetch status, segment counting
Calls	Create, list, get, update; TwiML fetch for `Say` / `Gather` / `Play` / `Hangup` / `Record`
Incoming phone numbers	Provision and list numbers
Verify v2	Create service, create verification, check code
Conversations	Create conversation, post and list messages
WhatsApp	Template-approved sends (`template:...` body); non-approved templates return `63016`
Status callbacks	POST to your app URL (captured in admin delivery logs)

Point the Twilio SDK at the clone with TWILIO_API_BASE or use route mode — see API & SDK.

Magic numbers

Twilio test magic numbers are built in:

Number	Behavior
`+15005550001`	Invalid `To`
`+15005550002`	Can't route
`+15005550003`	International permissions
`+15005550004`	Blocked
`+15005550006`	Valid mobile (default `From`)
`+15005550008`	No voice
`+15005550009`	Non-mobile (Verify may fail)

Seeds and initial state

There is no bundled otp-flow seed file. Options:

Approach	Example
Empty	Default Verify service; provision numbers via API
Admin JSON seed	`POST /_clone/seed` with `{ "phone_numbers": [{ "number": "+15005550006" }] }`
Dashboard preset	Phone OTP signup (`twilio` + `auth`) in the preset library

The seed string on start() controls deterministic OTP codes and account SIDs.

Limits

Limit	Detail
OTP lookup	`lastOTP()` / admin `GET /_clone/twilio/otp/{runId}?to=...` — deterministic per run
Message delivery	Advance clock (`3s` typical) to reach `delivered`
Chaos presets	`invalid_number`, `verify_expired`, `status_callback_fail`

Cross-clone flows

Phone OTP signup: combine Twilio + Auth clone. Use the Phone OTP signup preset in the dashboard library.

Environment variables

MOLAR_CLONE_TWILIO_URL, MOLAR_CLONE_TWILIO_ADMIN_URL

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