Understand message length, segments, and billing

Learn how CallHub counts characters, splits long texts into segments, and bills per segment, so you can write messages that cost what you expect. This applies to anyone sending texts through Text Broadcast or Peer to Peer texting campaigns.

Text messages are not billed per message. They are billed per segment, and one long message can quietly become three or four segments. Knowing where the split points are helps you trim a message by a few characters and cut its cost, spot when a single emoji has doubled your bill, and predict campaign spend before you hit send. A few minutes here can save real money on a large contact list.

How message length works

A single SMS holds:

• 160 characters when the message uses only GSM/ASCII characters (standard letters, numbers, and common punctuation).
• 70 characters when the message contains any Unicode character (emojis, accented letters, smart quotes, and most non-English scripts).

Go past that limit and the message splits into segments. Each segment reserves a few characters for reassembly data, so the per-segment capacity drops:

For example, a 200-character GSM message becomes two segments (153 + 47). A 200-character message with one emoji becomes three segments (67 + 67 + 66).

⚠ One emoji or special character makes the entire message Unicode. Your limit drops from 160 to 70 characters per message, which more than doubles the segment count for the same text and raises your cost.

What recipients see

CallHub sends multi-segment messages with concatenation data so carriers can rejoin them. What happens next depends on the recipient's network:

• GSM networks reassemble the segments and display them as one message.
• CDMA networks may deliver the segments as separate texts, sometimes out of order.

How billing works

Pricing is per segment, not per message. In the US, an SMS segment currently costs $0.034, so a three-segment message costs $0.102 total.

ⓘ You are billed for every segment your message splits into, not for the message as a whole. A message that reads as one text on the recipient's phone can still bill as three segments.

Check your message length before sending

As you type in your campaign's Script section, a counter below the message box shows the characters remaining and, once you pass the single SMS limit, the total character count and segment count. Your message is a single SMS when the counter shows one segment with characters still remaining.

If the limit drops to 70, your text contains Unicode. CallHub highlights the characters causing the drop so you can replace or remove them.

✓ Check the segment counter before every send, and trim or swap flagged characters to stay under a split point. If your message runs long, above roughly 500 characters, consider sending it as MMS instead. See SMS vs MMS to compare cost and delivery.

FAQs

Why was I charged for 3 SMS when I only sent one message? 
Your message exceeded the single SMS limit, so it split into three segments, and billing is per segment. Check the segment counter in the Script section; a 350-character GSM message, for example, bills as three segments even though it may arrive as one text.

Why did my character limit suddenly drop to 70? 
Your message contains at least one Unicode character, such as an emoji, an accented letter, or a smart quote pasted from another app. That switches the whole message to Unicode encoding, which caps a single SMS at 70 characters. CallHub highlights the characters responsible so you can remove them and restore the 160-character limit.

Do my recipients see one message or several? 
Usually one. On GSM networks, carriers rejoin the segments and show a single message. On CDMA networks, segments may arrive as separate texts and possibly out of order, so front-load the important information in long messages.