Unlimited SMS
Your unlimited SMS plan,
now usable by API.
Most mobile plans include unlimited texting. With the free Unlimited Messaging Android app, your code, your dashboard or your AI assistant sends those SMS from your own phone and number, with no per-message fee added. Here is what that covers, and the honest limits: carrier fair use and Android's sending cap.
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GeminiThe context
What does "unlimited SMS" cover, and how do you use it from code?
Unlimited SMS is a feature of consumer mobile plans: you pay a monthly price and send texts without counting them, as long as the traffic looks like a person's. The CTIA messaging principles describe that typical consumer traffic: at most around one message per second, and rarely more than a few hundred a day.
Until now, that allowance was only usable by hand, from the phone's messaging app. Sending SMS from code meant an A2P provider: a rented number, a price per 160-character segment that varies by country, and in the US a brand and campaign registration (A2P 10DLC) before the first message.
The free Unlimited Messaging Android app bridges the two. Install it, sign in, and your phone becomes an SMS gateway for your account: each POST /message with "channel": "SMS" leaves from your SIM, on your plan, from your number. Unlimited Messaging adds no per-message fee, and replies come back to your inbox and the message.received webhook.
"Unlimited" still has rules. Carriers sell these plans for personal use and usually forbid automated bulk sending, and Android asks you to confirm when an app sends more than about 30 SMS in a short window. The gateway respects both: it is built for your own traffic at a human pace, reminders, codes, follow-ups, not for mass campaigns.
Comparison
Unlimited SMS through your phone vs an A2P SMS provider
Two ways to send SMS from code. One uses the unlimited texting you already pay for, the other bills each segment but scales to campaigns.
| A2P SMS providerper billed segment | Your unlimited planvia Unlimited Messaging | |
|---|---|---|
| Price per SMS | Per 160-character segment, varies by country | Included in your plan, no fee added by us |
| Sender | Rented number or short code | Your own mobile number |
| Bulk campaigns | Allowed, with registration and opt-in rules | No: fair use and Android's cap keep it to a human pace |
| Setup | Number purchase, sender registration | Install the app and sign in |
| Replies | Webhook to your server | Your inbox and webhook, next to WhatsApp and email |
| Hardware | None | An Android phone kept on and connected |
| Delivery status | Carrier delivery receipts | Sent, delivered when your carrier reports it |
Our approach
Unlimited texting from code, the honest way
We send the SMS from your phone, on the plan you already pay for, and we pace them so your plan and your phone stay happy.
No per-SMS fee on top of your plan
The SMS is a normal text from your SIM. If your plan includes unlimited SMS, the API sends them within that allowance, and Unlimited Messaging adds nothing per message.
Paced for you
The API spaces SMS out to stay under Android's confirmation threshold, so your phone never stops to ask.
Every channel in one request
Add WhatsApp and email next to SMS in the same POST /message: up to three channels, one dispatchId.
Open source app
MIT licensed, no Firebase, no Play Services, no analytics. Check exactly what the app does with its SMS permissions.
- Per-SMS fee added by Unlimited Messaging
- 0Per-SMS fee added by Unlimited Messaging
- SMS per window before Android asks to confirm
- 30SMS per window before Android asks to confirm
- SIMs per phone, each its own SMS account
- 2SIMs per phone, each its own SMS account
- Channels in one request: WhatsApp, SMS, email
- 3Channels in one request: WhatsApp, SMS, email
Good to know
Getting the most out of your unlimited plan
An unlimited plan is made for personal messaging, and used that way it covers everyday sending from code very well. Three points to keep in mind.
Your own traffic, at a human pace
Reminders, codes and replies to people who expect to hear from you are exactly what it is for. Consumer plans exclude automated bulk sending, so marketing campaigns belong elsewhere.
Pacing handled for you
Android asks for a confirmation above 30 SMS in a short window. Unlimited Messaging spaces messages out automatically, so you do not have to think about it.
Long texts, handled
Messages up to 1,530 characters are split and reassembled automatically. For images and files, send the same request on WhatsApp or email.
How it works
Use your unlimited SMS from code in three steps
- 01
Install the Android app
Download the free APK from the Android page or GitHub Releases. It is not on Google Play, which reserves SMS permissions to default SMS apps.
- 02
Sign in
The website's own login opens in a browser tab: email, magic link, Google or GitHub. Each SIM then appears as an SMS account in your dashboard.
- 03
Send
POST /message with "channels": [{"channel": "SMS"}], or send from the dashboard, the SDKs, n8n or Claude and ChatGPT through the MCP server.
FAQ
Questions about unlimited SMS
Sources
Sources & references
To check the information in this article for yourself:
- Messaging Principles and Best Practices (May 2023)CTIA
- SmsUsageMonitor - Android's outgoing SMS limit (source code)Android Open Source Project
- Don't kill my app! - background limits by manufacturerdontkillmyapp.com
- Optimize for Doze and App StandbyAndroid Developers
- Unlimited Messaging for Android - source code and releasesGitHub
- SMS pricing - per segment and per countryTwilio
Written by
Ilian · Senior Software Engineer
A senior software engineer, he founds and runs several tech companies. He builds products around messaging APIs, automation and AI integration, and shares here what he learns while building.
Put your unlimited SMS plan to work.
Install the free Android app, sign in, and send your first SMS by API from your own number.