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.