MMS: definition and how it works
Published and updated
MMS (Multimedia Messaging Service) is the carrier messaging service for pictures, audio, video and long text, delivered over the mobile data connection rather than the signalling channel SMS uses.
How it works
SMS travels in the signalling channel of the mobile network in 140-byte segments. MMS is a different service built on top of it. The sender's phone uploads the content to the carrier's multimedia message centre over a data connection, and the recipient's phone receives an SMS notification and downloads the content. That indirection is why MMS needs a data plan on both ends, why a message can show as received before its picture loads, and why MMS between carriers or across borders is patchy.
The payload is a small multimedia document: images, short audio or video clips, and text with no practical length limit, up to a size cap each carrier sets, commonly a few hundred kilobytes to a megabyte. Carriers compress large images on the way through.
Pricing differs from SMS. A single MMS is billed as one message regardless of length, which makes it cheaper than a long concatenated SMS in some markets and far more expensive in others. Cloud providers price MMS at several times the SMS rate and support it mainly in North America.
For application messaging MMS is a niche: appointment reminders with a map, a receipt image, a coupon. Most transactional traffic is text, fits in one or two SMS segments, and does not need a data connection to arrive.
How this applies with textbee
textbee sends and receives SMS. If a use case needs an image, send a short SMS with a link the recipient can open instead, and keep the link out of OTP messages.
Related terms
- RCS: RCS (Rich Communication Services) is the carrier messaging standard meant to succeed SMS, adding read receipts, typing indicators, high-resolution media, group chat and verified business senders, delivered over data.
- Concatenated SMS: A concatenated SMS is a message longer than one segment that the sender splits into several SMS carrying a shared header, so the receiving phone can reassemble them into one text.
- SMS segment: An SMS segment is one physical text message of up to 140 bytes, the unit that networks carry and providers bill, so a long or non-Latin message counts as several segments.