Text messages
SMS, WhatsApp, email:
three channels, one API.
A text message to a customer can go out as an SMS, a WhatsApp message or an email. Each has its strengths: SMS reaches every phone, WhatsApp carries media and read receipts, email carries long content and files. With Unlimited Messaging, all three are channels of the same API, sent from your own number, SIM and mailbox.
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GeminiThe context
SMS, WhatsApp or email: which channel for a text message?
A text message used to mean one thing: an SMS of up to 160 characters per segment sent over the mobile network. Today the same message can reach your customer on three channels, each with its own reach, format and receipts.
SMS is the universal one. It reaches any mobile phone, iPhone or Android, with no app and no data connection, which makes it the safest channel for a short, urgent message. It is text only, and its receipts stop at "delivered", when the carrier reports it.
WhatsApp is where many people actually chat: more than 3 billion users, long messages, images and PDFs, and read receipts. Email carries the longest content, HTML layout and many attachments, and it is the channel people expect for documents, receipts and anything they will search for later.
Most businesses need more than one. With Unlimited Messaging, SMS (through our free Android app, from your own SIM), WhatsApp (from your linked account) and email (from your own mailbox) are three channels of the same POST /message endpoint. You choose per message, or send on all three in a single request, and every reply lands in the same inbox.
Comparison
SMS, WhatsApp and email side by side
The same text message, three channels. Here is what each one does well and where it stops, as sent through Unlimited Messaging.
| SMSyour Android phone | WhatsAppyour linked account | Emailyour mailbox | |
|---|---|---|---|
| Reach | Any mobile phone, no app or data needed | 3 billion+ users, needs the app and data | Anyone with an email address |
| Sender | Your own mobile number | Your own WhatsApp number | Your own email address |
| Length | 1,530 characters, up to 10 parts | 1,600 characters per message | Long text and HTML |
| Media | Text only, no MMS | One image, PDF or audio file | Up to 20 attachments |
| Receipts | Delivered when the carrier reports it, no read | Delivered and read | No native read receipt |
| Replies | Inbox and webhook | Inbox and webhook | Inbox and webhook |
| Volume | Human pace: carrier fair use, Android cap | Paced sending from your account | Your mail provider's sending limits |
| Best for | Short urgent alerts, codes, people offline | Conversations, reminders, media | Documents, receipts, long content |
SMS through the Unlimited Messaging Android app, WhatsApp through your linked account, email through your own mailbox. Limits as of November 2026.
Our approach
One API, the channel is just a field
Validation, queueing, statuses and webhooks are the same for every channel. Only the transport changes: your phone, your WhatsApp account or your mailbox.
One request, up to three channels
List WHATSAPP, SMS and EMAIL in channels: each one gets its own message, all linked by one dispatchId. Override the text per channel, for instance a shorter SMS.
One inbox for every reply
SMS, WhatsApp and email replies arrive in the same inbox and the same message.received webhook.
Your own identities
Your mobile number, your WhatsApp account, your email address. No rented sender, no shared domain.
Everywhere you work
Dashboard, REST API, TypeScript and Python SDKs, n8n, and the MCP server for Claude, ChatGPT and Cursor.
- Channels per request: SMS, WhatsApp, email
- 3Channels per request: SMS, WhatsApp, email
- Inbox and webhook for every reply
- 1Inbox and webhook for every reply
- Characters max per SMS
- 1530Characters max per SMS
- Attachments max per email
- 20Attachments max per email
The request
The same message on SMS, WhatsApp and email at once
Give the recipient's phone and email in to, list the channels, and write the text once. Each channel can override it: here the SMS gets a shorter version, while WhatsApp and email get the full text.
{
"to": {
"phone": "+33612345678",
"email": "[email protected]"
},
"subject": "Your order #1042 has shipped",
"text": "Hello, your order #1042 has shipped and will arrive Thursday. Track it from your account or reply to this message with any question.",
"channels": [
{
"channel": "WHATSAPP"
},
{
"channel": "SMS",
"text": "Your order #1042 has shipped, arriving Thursday."
},
{
"channel": "EMAIL"
}
]
}How it works
Connect your channels, then send
- 01
Create your account
Sign up for free, then connect the channels you want: scan a QR code for WhatsApp, add your mailbox for email.
- 02
Add SMS with your phone
Install the free Android app and sign in. Each SIM becomes an SMS account, sending from your own number.
- 03
Send on any channel
Create an API key and call POST /message with one, two or three channels. Statuses and replies come back by webhook.
FAQ
Questions about SMS, WhatsApp and email
Sources
Sources & references
To check the information in this article for yourself:
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.
Reach your customers on the channel they read.
Create your free account, connect WhatsApp, email and your Android phone, and send your first multi-channel message.