# Unlimited SMS by API: is it really unlimited?

> Your plan already includes unlimited SMS. A free Android app lets you send them by API from your own number, within carrier fair use and Android limits.

Source: https://unlimitedmessaging.app/articles/unlimited-sms

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.

[Download the Android app](https://unlimitedmessaging.app/channels/sms)[Create a free account](https://app.unlimitedmessaging.app)

The 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](https://api.ctia.org/wp-content/uploads/2023/05/230523-CTIA-Messaging-Principles-and-Best-Practices-FINAL.pdf) 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.

![Drawing of the Unlimited Messaging app showing connected WhatsApp numbers and mailboxes, with the headline “Truly unlimited SMS doesn't exist”.](https://unlimitedmessaging.app/_next/image?url=%2Fassets%2Farticles%2Fcovers%2Funlimited-sms-en.png&w=3840&q=75)

Definition
Unlimited SMS

A mobile plan allowance with no per-message charge for SMS you send person to person, within the carrier's fair-use terms.

Also sold as unlimited texting, unlimited texts or infinite SMS.

[Source: Messaging Principles and Best Practices - CTIA↗](https://api.ctia.org/wp-content/uploads/2023/05/230523-CTIA-Messaging-Principles-and-Best-Practices-FINAL.pdf)

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.

__Unlimited SMS through your phone vs an A2P SMS provider__
| 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.

1. 01  
### Paced for you  
The API spaces SMS out to stay under Android's confirmation threshold, so your phone never stops to ask.
2. 02  
### Every channel in one request  
Add WhatsApp and email next to SMS in the same POST /message: up to three channels, one dispatchId.
3. 03  
### 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.

1. 01  
### 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.
2. 02  
### 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.
3. 03  
### 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.

Good to know

### Planning a marketing campaign to thousands of numbers?

Then a personal unlimited plan is the wrong tool, whatever the app. Use an A2P SMS provider with opt-in management, or reach those customers on WhatsApp or email through the same Unlimited Messaging API.

How it works

## Use your unlimited SMS from code in three steps

1. 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.
2. 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.
3. 03  
### Send  
POST /message with "channels": \[{"channel": "SMS"}\], or send from the dashboard, the SDKs, n8n or Claude and ChatGPT through the MCP server.

Key takeaway

### Unlimited SMS, used by your code, within the rules.

If your plan includes unlimited texting, the Unlimited Messaging Android app lets your code send those SMS from your own number without a per-message fee on top. Keep it to your own traffic at a human pace, and use WhatsApp, email or an A2P provider for anything that looks like a campaign.

FAQ

## Questions about unlimited SMS

You can send SMS by API within your plan's allowance. If your plan includes unlimited texting, the SMS sent through the Unlimited Messaging Android app use it, with no per-message fee added by us. Fair use and Android's sending cap still apply, so it is unlimited at a human pace, not for mass campaigns.

Sending your own messages from your phone is normal use. What consumer plans usually forbid is automated bulk sending, such as marketing blasts. Check your carrier's terms, and keep the gateway for reminders, codes and conversations with people who expect your messages.

Android protects users from apps that send SMS behind their back: past 30 SMS in its check window, it asks for confirmation. Unlimited Messaging spaces messages out so the phone does not stop to ask.

No per-message fee. The SMS goes on your carrier plan. On the free plan, messages end with a short "Sent with UnlimitedMessaging.app" line, as on WhatsApp and email.

Yes. SMS that reach your phone after you sign in come back to your Unlimited Messaging inbox and to the message.received webhook. Older SMS already on the phone are never read or imported.

The gateway is Android only, version 8.0 or newer: iOS does not let apps send SMS in the background. An old Android phone with a SIM is enough.

Then add WhatsApp to the same request, or use email. Both are channels of the same Unlimited Messaging API, with their own statuses and replies in the same inbox.

Sources

## Sources & references

To check the information in this article for yourself:

1. [01Messaging Principles and Best Practices (May 2023)↗CTIA](https://api.ctia.org/wp-content/uploads/2023/05/230523-CTIA-Messaging-Principles-and-Best-Practices-FINAL.pdf)
2. [02SmsUsageMonitor - Android's outgoing SMS limit (source code)↗Android Open Source Project](https://android.googlesource.com/platform/frameworks/opt/telephony/+/refs/heads/main/src/java/com/android/internal/telephony/SmsUsageMonitor.java)
3. [03Don't kill my app! - background limits by manufacturer↗dontkillmyapp.com](https://dontkillmyapp.com/)
4. [04Optimize for Doze and App Standby↗Android Developers](https://developer.android.com/training/monitoring-device-state/doze-standby)
5. [05Unlimited Messaging for Android - source code and releases↗GitHub](https://github.com/UnlimitedMessaging/unlimited-messaging-android)
6. [06SMS pricing - per segment and per country↗Twilio](https://www.twilio.com/en-us/sms/pricing)

![Ilian, senior software engineer](https://ilianazz.com/images/iliazz.png)

Written by

[Ilian](https://unlimitedmessaging.app/authors/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.

[View LinkedIn profile↗](https://www.linkedin.com/in/ilianAzz/)Updated November 7, 2026

![](https://unlimitedmessaging.app/assets/logos/whatsapp.svg)![](https://unlimitedmessaging.app/assets/logos/email.svg)![](https://unlimitedmessaging.app/assets/logos/sms.svg)

## 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.

[Get the Android app→](https://unlimitedmessaging.app/channels/sms)

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