SMS and iMessage API: developer quick start

Quick start: send your first SMS

You need a VoidFix SMS account with at least one Android phone connected. If you haven't connected one yet, follow the Android device connection guide first.

1. Copy your API key from the portal

   Log in to the SMS portal and open API in the left menu, or go straight to sms.voidfix.com/api.php. Copy the key shown there. Every request sends it as the key parameter.

2. Find the ID of the device you'll send from

   List the phones connected to your account and note the device ID you want to use.

   curlCopyCopied

   curl "https://sms.voidfix.com/services/get-devices.php?key=YOUR_API_KEY"

3. Send a single SMS

   Post a form-encoded request to /services/send.php with your key, the recipient in international format, the message and the device ID.

   curlCopyCopied

   curl -X POST "https://sms.voidfix.com/services/send.php" \
     -H "Content-Type: application/x-www-form-urlencoded" \
     --data-urlencode "key=YOUR_API_KEY" \
     --data-urlencode "number=+15551234567" \
     --data-urlencode "message=Hi Sam, your appointment is tomorrow at 10am." \
     --data-urlencode "devices=YOUR_DEVICE_ID"

   The raw request looks like this:

   HTTPCopyCopied

   POST https://sms.voidfix.com/services/send.php
   Content-Type: application/x-www-form-urlencoded
   
   key=YOUR_API_KEY&number=+15551234567&message=Hi! Your appointment is tomorrow at 10am.&devices=215

4. Check the message status

   Look the message up by its ID, or list messages by status, with /services/read-messages.php. You can also watch it move from pending to delivered in the dashboard.

   curlCopyCopied

   curl "https://sms.voidfix.com/services/read-messages.php?key=YOUR_API_KEY&id=MESSAGE_ID"

Base URL and authentication

• Base URL for SMS, MMS and iMessage: https://sms.voidfix.com
• Authentication: your account API key, passed as the key parameter on every request. Find it in the portal's API section.
• Phone numbers: use international format, for example +15551234567.
• WhatsApp uses separate API keys from the WhatsApp portal. See WhatsApp API keys below.

SMS and MMS endpoints

Send a single SMS or MMS

POST /services/send.php with these parameters:

To send an MMS, add isMMS=true and the media URL in attachments:

curl -X POST "https://sms.voidfix.com/services/send.php" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  --data-urlencode "key=YOUR_API_KEY" \
  --data-urlencode "number=+15551234567" \
  --data-urlencode "message=Here is your order photo." \
  --data-urlencode "devices=YOUR_DEVICE_ID" \
  --data-urlencode "isMMS=true" \
  --data-urlencode "attachments=https://example.com/photo.jpg"

Send bulk messages

The same endpoint sends many messages in one request. Instead of number and message, pass a messages array.

Each item in messages has this shape. Accepted type and option values are listed in the full SMS API reference.

{
  "number": "+15551234567",
  "message": "{Hi|Hello} Sam, your order has shipped.",
  "type": "...",
  "attachments": ""
}

Read, resend and manage contacts

• Read messages: GET /services/read-messages.php with key plus one of id, groupId or status. When filtering by status you can add deviceID, simSlot, startTimestamp and endTimestamp.
• Resend: POST /services/resend.php with key and either id, or groupId with a status. Useful for messages that failed while a phone was offline.
• Contacts: POST /services/manage-contacts.php with key, listID and number. Add name and resubscribe to add a contact, or unsubscribe=true to opt a contact out.
• Contact lists: GET /ajax/zapier/get-contacts-list.php lists them, and POST /ajax/services/create-contacts-list.php with key and name creates one.

iMessage API endpoints

The iMessage API uses the same base URL and API key. You need an active iMessage line, and each line can message up to 50 unique contacts per day.

Request bodies, field types and a try-it console are in the iMessage API documentation.

WhatsApp API keys

WhatsApp runs in its own portal. Generate API keys at Tools, Keys in the WhatsApp portal (wa.voidfix.com/dashboard/tools/keys) and use them with GoHighLevel, Zapier, Make, Zoho, HubSpot or your own code. For custom WhatsApp API requirements, talk to the team.

Delivery status, replies and webhooks

Messages move through these statuses, which you can see in the dashboard and query with read-messages.php: pending, queued, scheduled, delivered and failed. A phone has to be online with the VoidFix service running to send and receive. If it goes offline, messages wait as pending or queued, and any that fail can be resent by ID or group ID.

Replies show up in your dashboard, and in your CRM if you use a native integration like GoHighLevel. Tools like Zoho and Make use a webhook or HTTP step to call send.php, as shown in the Zoho and Make guides. For webhook details beyond that, check the full SMS API reference or ask our team.

No-code and low-code guides

Full API references

• SMS and MMS API reference on sms.voidfix.com
• iMessage API documentation
• All integrations, including HubSpot, N8N, Pabbly and Bitrix24

Get help with your integration