Deciding whether to send plain text or text with media? This article explains what SMS and MMS each do, how they differ, and which one fits your message, audience, and budget.
The format you pick affects three things: what your message can contain, how much it costs, and how many people engage with it. SMS is the reliable default for short, urgent updates. MMS lets you add images, video, or audio, and MMS messages tend to see higher engagement rates (8% or more) and often result in better conversions. Picking the right format before you build your campaign saves credits and gets you better results.
What is SMS?
SMS (Short Message Service) is a plain-text message. You cannot attach media, but you can include links and other details in the text.
- Text only, up to 160 characters per message segment.
- Messages longer than 160 characters are charged as multiple messages.
- Works on virtually every mobile phone, everywhere.
Use SMS when your message is short and direct: reminders, confirmations, quick calls to action, or a link to something bigger.
What is MMS?
MMS (Multimedia Messaging Service) is an enhanced version of SMS that supports multimedia content along with plain text. You can send images, videos, audio, GIFs, and text together in one message.
- Media plus up to 1,600 characters of text.
- Maximum total message size is 5 MB.
- Higher engagement rates (8% or more) than text-only messages.
Use MMS when a visual carries the message: event flyers, candidate photos, product shots, or any longer message where one attachment does the work of several paragraphs.
ⓘ MMS is available only in the US and Canada. If your contacts are outside these countries, use SMS. See MMS availability and carrier support.
How SMS and MMS differ
| SMS | MMS | |
|---|---|---|
| Content | Plain text only (links allowed) | Images, videos, audio, GIFs, and text together |
| Text length | 160 characters per segment; longer texts are billed as multiple segments | Up to 1,600 characters |
| Message size | Text only | Up to 5 MB total, including media |
| Engagement | Standard | Higher (8% or more), often better conversions |
| Availability | Worldwide | US and Canada only |
| Best for | Short, urgent, universal messages | Visual, longer, higher-impact messages |
Which should you pick?
- Short message, any country: SMS.
- You need an image, video, or audio file: MMS.
- Long message (over about 500 characters) to US or Canada contacts: MMS. In the US and Canada, messages over 500 characters are usually cheaper and more engaging sent as a single MMS than as multiple SMS segments.
ⓘ Billing works by segment. Any SMS over 160 characters is charged as multiple SMS segments, so a 450-character text costs three segments. See Understand message length, segments, and billing before you write long messages.
✓ If your message runs past about 500 characters, switch to MMS. One MMS often costs less than the four or more SMS segments the same text would use, and it engages better.
FAQs
Can I send an MMS without any media attached?
MMS is designed to carry media with text. If your message is text only and under 160 characters, SMS is the simpler and cheaper choice. For long text-only messages in the US and Canada, MMS can still be the cheaper option because of segment billing.
What files can I attach to an MMS?
Common image, video, and audio formats are supported within the 5 MB total message size. See Supported file types and size limits for MMS for the full list.
Why can't my contacts outside the US receive my MMS?
MMS delivery through CallHub is limited to the US and Canada. See MMS availability and carrier support.
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