> For a complete index of all SignalWire documentation pages, fetch https://signalwire.com/docs/llms.txt

# 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                      |