Messaging MIME Types
To send MMS, you must include a media attachment. The content-type header must have an accepted content type, or SignalWire will have to reject the request.
Media Size Limits
The overall size limit is 1.2MB for local numbers and 750KB for toll-free numbers. Most carriers support message attachments with a total size of 1MB-1.2MB. However, to maximize deliverability across all carriers, limit your attachment size to 500KB.
Accepted MIME Types
All of the following MIME types are accepted. SignalWire will not modify the body content for device compatibility.
| Type | Description |
|---|---|
| audio/mp4 | mpeg layer 4 audio |
| audio/mpeg | mpeg layer 3 audio |
| audio/mpeg3 | mpeg layer 3 audio |
| audio/ogg | ogg audio |
| audio/vorbis | audio compression format |
| audio/vnd.wav | wav format audio |
| audio/ac3 | codec format audio |
| audio/amr | codec format audio |
| audio/midi | musical instrument digital interface format |
| image/jpeg | jpeg format image |
| image/gif | graphics interchange format |
| image/png | portable network graphics format |
| image/bmp | bitmap image format |
| text/plain | text file format |
| text/calendar | text file format |
| text/vcard | text file format |
| text/x-vcard | text file format |
| video/mpeg | mpeg video format |
| video/mp4 | mpeg layer 4 video format |
| video/quicktime | quicktime video |
| video/h264 | video compression format |
| video/3gp | media container format |