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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.

audio/mp4mpeg layer 4 audio
audio/mpegmpeg layer 3 audio
audio/mpeg3mpeg layer 3 audio
audio/oggogg audio
audio/vorbisaudio compression format
audio/vnd.wavwav format audio
audio/ac3codec format audio
audio/amrcodec format audio
audio/midimusical instrument digital interface format
image/jpegjpeg format image
image/gifgraphics interchange format
image/pngportable network graphics format
image/bmpbitmap image format
text/plaintext file format
text/calendartext file format
text/vcardtext file format
text/x-vcardtext file format
video/mpegmpeg video format
video/mp4mpeg layer 4 video format
video/quicktimequicktime video
video/h264video compression format
video/3gpmedia container format