MMS (Multimedia Messaging Service) extends SMS with support for images, video, audio, PDFs and other media. Available in the United States, Canada, and Australia only.

Prerequisites

A service plan with an MMS-capable number (US/CA/AU long code or toll-free).
A Conversation API app in the same region as your service plan.
MMS channel setup requires: Account ID, API key, default originator or short code, username and password.

SDK Reference

Supported Media Types

Media Type	Common Formats	Notes
Image	JPEG, PNG, GIF, BMP	Most widely supported
Video	MP4, 3GPP	Quality may be reduced for delivery
Audio	MP3, WAV, AMR	Limited carrier support
vCard	VCF	Contact cards
Text	Plain text	Included as message body
PDF	PDF	Included as PDF file

All media files must serve a valid Content-Type header. application/octet-stream may be rejected.

File Size Limits

Keep media under 1 MB for reliable delivery.

Number Type	Typical Max	Notes
Long code	~1 MB	Varies by carrier
Toll-free	~1 MB	Varies by carrier
Short code	Varies
10DLC	Varies

MMS Channel Properties

Property	Description
`MMS_SENDER`	Sender phone number
`MMS_STRICT_VALIDATION`	Validate media against best practices (default: false)

Card Messages via MMS

Card title becomes the MMS Subject line (max 80 chars, 40 recommended). Title is not duplicated in body.

Unsupported Message Types (Transcoded to Text)

Choice messages (buttons/quick replies)
Carousel messages
Location messages

Message Examples

Send MMS / Fallback patterns — See Messages API Reference. Set channel to MMS and include MMS_SENDER in channel_properties. For fallback, add channel_priority_order array with both MMS and SMS channel identities.
MMS message support details — See MMS Channel Overview.

MMS Gotchas

US, Canada, and Australia only. Use WhatsApp, RCS, or SMS for international media messaging.
Keep files under 1 MB. Carrier limits are ~1 MB. Oversized media is compressed or rejected.
Base64 overhead. Binary content encoded with Base64 produces files ~37% larger.
Content-Type headers required. Media URLs must return valid MIME types. Generic application/octet-stream may be rejected.
Media URLs must be publicly accessible. URLs behind auth or firewalls fail.
Short code/10DLC MMS limitations. Transcoding not supported. Size limits vary by operator.
Video quality reduction. Video may be compressed significantly. For high-quality video, send a link via SMS.
Rich messages degrade. Carousels, choices, and location are transcoded to plain text.
No read receipts. MMS does not provide read receipts. Some carriers return delivery confirmations.