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 |