What is an SMS segment?
An SMS segment is the billing unit used to carry a text message through the mobile network. HighLevel's current documentation describes a standard GSM-7 SMS segment as up to 160 characters. When the text is longer, it is split into multiple segments for transport and billing.
Why 161 characters can cost more than 160
If a plain-text message stays within the single-segment limit, it is generally billed as one segment. Once it crosses the limit, the carrier must split the content into multiple pieces and reassemble it on the recipient's phone. From the user perspective it still looks like one text bubble, but the billing system sees multiple units.
| Message example | What happens | Cost effect |
|---|---|---|
| Short plain text | Typically one GSM-7 segment | Lowest segment count |
| Longer plain text | Split into multiple segments | Cost rises with segment count |
| Emoji or Unicode character | Can switch message to UCS-2 encoding | Single-segment capacity can fall to 70 characters |
| Long Unicode message | Concatenated UCS-2 segments use less payload per segment | Segment count can rise quickly |
Why emojis can surprise agency owners
HighLevel specifically warns that emojis and other non-GSM-7 characters can trigger Unicode/UCS-2 encoding. In that mode, a single SMS segment holds only 70 characters, and concatenated Unicode segments can carry up to 67 characters each because some capacity is reserved for joining the parts together.
That means adding one emoji to an otherwise inexpensive text can change the encoding of the entire message. A text that looked comfortably under 160 characters may suddenly require several segments.
Carrier fees are multiplied by segment count too
HighLevel's cost formula includes both the base per-segment SMS rate and carrier fees. If a message becomes five segments, both portions are applied across those five segments. This is one reason a small change in copy can materially change total messaging cost at agency scale.
How agencies can reduce segment waste
- Keep automated reminders concise.
- Test messages that use emojis or special punctuation.
- Avoid pasting styled text from documents without checking for hidden Unicode characters.
- Review the segment count before launching large campaigns.
- Use links strategically rather than adding unnecessary copy.
Why this matters for client pricing
If your agency bills clients a fixed monthly fee while your provider bills you by segment, your margin depends partly on message composition. A high-volume client with long, emoji-heavy automation can cost considerably more than another client sending the same number of visible messages.
That is one reason some agencies prefer a flat-rate SMS platform layer. With ASG, there is no per-message ASG platform fee, although the Android device, carrier plan, carrier fair-use rules, and other third-party costs remain separate.