| Dimension | SMS | MMS |
|---|---|---|
| Content | Plain text only | Images, audio, video, longer text |
| Length | 160 characters per segment | Commonly up to 1,600 characters |
| Transport | Cellular signalling channel | Needs a data connection to retrieve |
| Size limit | Not applicable | Carrier-capped, commonly around 1MB in the US |
| Reach | Virtually every mobile phone | Almost all, older handsets can struggle |
| Relative cost | The baseline rate | Close to four times SMS on our published card |
| Branding | Anonymous number or short code | Anonymous number or short code |
Why an SMS splits into several messages
The 160-character limit is a property of the encoding, not a style guide. Type past it and the message is split into segments and reassembled on the handset, and you are billed for each segment rather than for the message. Concatenation costs a few characters of overhead per part, so segments after the first carry about 153 characters. Using a single emoji or a curly apostrophe can switch the whole message to a different encoding and cut the limit to 70 characters, which is how a message that looks slightly too long quietly bills as three.
What MMS actually buys you, and what it costs
MMS was the first way to put a picture in a text, and that is still the reason to use it. The trade is real though. It needs a data connection at the receiving end, carriers compress images and cap the payload, and it prices at close to four times the SMS rate on our published card. There is also no branding: an MMS arrives from the same anonymous number an SMS does, so the recipient has no way to tell your promotion from a scam except by reading it.
Which one a business should send
Send SMS for anything where the words are the payload: one-time passcodes, appointment reminders, delivery notifications, account alerts. It is cheaper, it reaches everyone, and it does not depend on the recipient having data at that moment.
Send MMS when the image is the point and not decoration, which in practice means a product shot, a coupon, or an event graphic. Paying four times the rate to attach a logo to a text nobody needed a picture for is the most common way messaging budgets leak.
Both are A2P traffic in the US, so both require 10DLC brand and campaign registration before a carrier will deliver them at volume. That paperwork is the same either way, which surprises teams who assume plain SMS is exempt.
Where RCS changes the question
RCS is the successor to both. It carries the media MMS carries, adds carousels and tappable buttons MMS never had, and puts your verified brand name, logo, and a checkmark at the top so the recipient knows who is writing before reading a word. It also reports reads and taps, where SMS gives only a delivery receipt and MMS little more.
The reason this is not simply a replacement is reach. RCS needs a capable handset, so any serious program sends RCS where it lands and falls back to SMS or MMS automatically where it does not. That is how one send reaches the whole list rather than only the modern half of it.
- SMS is 160 characters per segment and text only; longer messages split and bill per segment.
- A single emoji can switch the encoding and drop the per-segment limit to 70 characters.
- MMS adds media and longer text but needs data, is carrier-capped around 1MB, and costs close to four times SMS.
- Neither SMS nor MMS carries brand identity; both arrive from an anonymous number.
- Both need 10DLC registration for US business sending.