# Send SMS by API from your own number: why pay per message? > A free open source Android app turns your phone into an SMS gateway: send by API from your own SIM and plan, no per-SMS fee added, replies included. Source: https://unlimitedmessaging.app/articles/sms SMS by API # Send SMS by API, _from your own number._ Install the free Android app, sign in, and every SMS you send through the Unlimited Messaging API leaves from your phone's SIM card, on your own carrier plan. Recipients see your number, replies come back to your inbox and webhooks, and the same request can also go out on WhatsApp and email. [Download the Android app](https://unlimitedmessaging.app/channels/sms)[Create a free account](https://app.unlimitedmessaging.app) The context ## What does sending SMS by API from your phone mean? Sending SMS by API from your own number means your code calls a REST endpoint, and the text leaves as a normal SMS from a phone you own. With Unlimited Messaging, that phone runs our [free, open source Android app](https://github.com/UnlimitedMessaging/unlimited-messaging-android). Classic SMS APIs work differently. You rent a sender number or a short code from a provider, the message travels over the A2P (application-to-person) network, and each segment of 160 characters is billed, at a rate that changes from one country to the next. In the United States you also register a brand and a campaign (A2P 10DLC) before sending. With the Android app, the phone keeps one connection open to the Unlimited Messaging API. When you call POST /message with "channel": "SMS", the API hands the message to the phone, the phone sends it from its SIM, and each status comes back as the network confirms it: queued, sending, sent, delivered when your carrier returns delivery reports, undeliverable or failed. SMS has no read receipts, so there is no "read" status. The SMS goes on your own plan, so Unlimited Messaging adds no per-message fee, and recipients see the number they already know. SMS received after you sign in come back to your inbox and the message.received webhook. It suits your own traffic at a human pace: reminders, codes, follow-ups, an AI agent texting your customers. Bulk campaigns still belong to a dedicated SMS provider. ![Illustration: a phone with text-message bubbles and an SMS tag, with the headline “SMS caps you at 160 characters”.](https://unlimitedmessaging.app/_next/image?url=%2Fassets%2Farticles%2Fcovers%2Fsms-en.png&w=3840&q=75) Definition Android SMS gateway An Android phone running an app that receives messages queued by an API and sends them as ordinary SMS from its own SIM card, then reports their status. Also called a phone SMS gateway or self-hosted SMS gateway. [Source: SmsManager - Android Developers↗](https://developer.android.com/reference/android/telephony/SmsManager) The request ## One curl to send an SMS, one more line to add WhatsApp and email The SMS channel uses the same POST /message endpoint as WhatsApp and email. Name it in channels, give a phone number, and it leaves from your phone. Add up to three channels to reach the same person everywhere in one request. curlShell ``` curl https://api.unlimitedmessaging.app/message \ -H "Authorization: Bearer $UM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "to": { "phone": "+33612345678" }, "channels": [ { "channel": "SMS" } ], "text": "Your appointment is tomorrow at 10:00." }' ``` An SMS from your own SIM. With dual SIM, add "accountId" to the channel entry to pick the line. POST /messageJSON ``` { "to": { "phone": "+33612345678", "email": "client@example.com" }, "subject": "Your appointment tomorrow at 10:00", "text": "Hello, this is a reminder that your appointment is tomorrow at 10:00. Reply to this message if you need to move it.", "channels": [ { "channel": "WHATSAPP" }, { "channel": "SMS", "text": "Your appointment is tomorrow at 10:00." }, { "channel": "EMAIL" } ] } ``` One request, three messages: each channel gets its own copy, sharing one dispatchId. The SMS entry overrides the text with a shorter version. Comparison ## Classic SMS API vs SMS from your own phone Both send an SMS from your code. They do not suit the same jobs: here is where each one is the better choice, honestly. __Classic SMS API vs SMS from your own phone__ | Classic SMS APITwilio-style, A2P | Unlimited Messagingyour Android phone | | | -------------------------------- | --------------------------------------------------- | ------------------------------------------------------- | | Sender | A number or short code rented from the provider | Your own number, the one your customers know | | Cost per SMS | Billed per 160-character segment, varies by country | Your carrier plan, no per-SMS fee added by us | | Setup | Buy a number, register sender (A2P 10DLC in the US) | Install the app, sign in, your SIM appears | | Volume | High throughput, built for campaigns | Human pace, about 30 SMS per window before Android asks | | Infrastructure | Nothing to keep running on your side | A phone that stays on, charged and connected | | Replies | Webhook to your server | Same inbox and webhook as WhatsApp and email | | Other channels | SMS only, or separate products | WhatsApp, email and SMS in one request | | Delivery status | Carrier delivery receipts | Sent, and delivered when your carrier reports it | Our approach ## SMS as one more channel of the same API We did not build an SMS provider. We made your phone a channel of the API you already use for WhatsApp and email, with the same statuses, webhooks, SDKs and MCP server. ### Your SIM, your number, your plan The SMS leaves from the phone in your pocket or on a desk at the office. Recipients see your usual number, and the cost is whatever your carrier plan already charges. 1. 01 ### Two-way SMS received after you sign in come back to your inbox and the message.received webhook, next to your WhatsApp and email conversations. 2. 02 ### Dual SIM Each SIM becomes its own SMS account. Pick the line per message with accountId, or let the API choose. 3. 03 ### Open source, no tracking The app is MIT licensed, with no Firebase, no Play Services and no analytics. You can read exactly what an app holding SMS permissions does. Per-SMS fee added by Unlimited Messaging 0Per-SMS fee added by Unlimited Messaging Channels in one request: WhatsApp, SMS, email 3Channels in one request: WhatsApp, SMS, email Characters max per SMS, sent in up to 10 parts 1530Characters max per SMS, sent in up to 10 parts Android version required 8.0+Android version required How it works ## From zero to your first SMS in three steps 1. 01 ### Install the app Download the APK on your Android phone from the Android page or GitHub Releases. It is not on Google Play, which reserves SMS permissions to default SMS apps. If Play Protect blocks the install or Android refuses the SMS permission, the FAQ below shows how to unblock it. 2. 02 ### Sign in Tap Sign in: the website's own login opens in a browser tab (email, magic link, Google or GitHub). The app never sees your password, and each SIM appears as an SMS account. 3. 03 ### Send Call POST /message with "channel": "SMS", or send from the dashboard, the SDKs, n8n or an AI assistant through the MCP server. Statuses and replies arrive by webhook. Key takeaway ### Your number, your plan, one API for every channel. For your own traffic, reminders, codes, follow-ups, replies, sending SMS from your phone gives you your real number, no per-message fee on top of your plan and replies in the same inbox as WhatsApp and email. For mass campaigns at high throughput, a classic SMS provider remains the right tool. FAQ ## Questions about sending SMS by API from your phone Install the Android app, sign in with your Unlimited Messaging account, then call POST /message with "to": {"phone": "+33612345678"}, "channels": \[{"channel": "SMS"}\] and your text. The message leaves from your phone's SIM card. No. The SMS is sent by your own phone, so it goes on your carrier plan. Unlimited Messaging adds no per-message fee. On the free plan, messages end with a short "Sent with UnlimitedMessaging.app" line, as on WhatsApp and email. At a human pace, yes. Android asks for confirmation once an app sends about 30 SMS in a short window, so the API spaces SMS out. Consumer "unlimited SMS" plans also usually forbid automated bulk sending. For mass campaigns, use a dedicated SMS provider. Google Play reserves the SMS permissions to the phone's default SMS app, with a few narrow exceptions. The app is distributed as an APK on GitHub Releases, and its source code is public under the MIT license. This is how Android treats any app installed outside Google Play, not a problem with the app. If Play Protect refuses the install, open the Play Store, tap your profile picture, then Play Protect, the settings icon, and temporarily turn off "Scan apps with Play Protect" while you install the APK (you can turn it back on afterwards). If the SMS permission is greyed out with a "Restricted setting" message, open Settings, Apps, Unlimited Messaging, tap the three dots in the top right corner, choose "Allow restricted settings", then go back to the app and grant the SMS permission. You get queued, sending, sent, delivered, undeliverable and failed statuses by webhook. "Delivered" depends on your carrier sending delivery reports, which not all do. SMS has no read receipts, so there is no "read" status. Yes. The SMS channel works with the dashboard, the REST API, the TypeScript and Python SDKs, the n8n node and the MCP server, so Claude, ChatGPT or Cursor can text from your phone when you ask them. No. The SMS channel sends text only (no MMS), up to 1,530 characters split into at most 10 parts. For an image or a PDF, add WhatsApp or email to the same request. Sources ## Sources & references To check the information in this article for yourself: 1. [01Unlimited Messaging for Android - source code and releases↗GitHub](https://github.com/UnlimitedMessaging/unlimited-messaging-android) 2. [02SmsManager - API reference↗Android Developers](https://developer.android.com/reference/android/telephony/SmsManager) 3. [03Use of SMS or Call Log permission groups↗Google Play Console Help](https://support.google.com/googleplay/android-developer/answer/10208820) 4. [04How long can a message be? SMS segments and character limits↗Twilio](https://www.twilio.com/docs/glossary/what-sms-character-limit) 5. [05SMS pricing - per segment and per country↗Twilio](https://www.twilio.com/en-us/sms/pricing) 6. [06A2P 10DLC - registration for application messaging in the US↗Twilio](https://www.twilio.com/docs/messaging/compliance/a2p-10dlc) ![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) ## Turn your phone into an SMS gateway. Download the free Android app, sign in, and send your first SMS by API from your own number today. [Get the Android app→](https://unlimitedmessaging.app/channels/sms) Similar articles * [![](https://unlimitedmessaging.app/_next/image?url=%2Fassets%2Farticles%2Fcovers%2Fandroid-sms-gateway-comparison-en.png&w=3840&q=75)What is the best Android SMS gateway? 2026 comparisonAndroidSMSGate, httpSMS, textbee and Unlimited Messaging: self-hosting, MMS, dual SIM, encryption, MCP.](https://unlimitedmessaging.app/articles/android-sms-gateway-comparison) * [![](https://unlimitedmessaging.app/_next/image?url=%2Fassets%2Farticles%2Fcovers%2Fai-agent-send-sms-en.png&w=3840&q=75)Can Claude or ChatGPT send SMS for you? Yes, here is howSMSAn AI assistant texts from your own Android phone and number over MCP, and asks before each send.](https://unlimitedmessaging.app/articles/ai-agent-send-sms) * [![](https://unlimitedmessaging.app/_next/image?url=%2Fassets%2Farticles%2Fcovers%2Funlimited-sms-en.png&w=3840&q=75)Unlimited SMS by API: use the plan you already pay forUse your plan's unlimited texting from code, through your own phone, within fair use and Android limits.](https://unlimitedmessaging.app/articles/unlimited-sms)