Avoiding excessive SMS message segmentation

This article provides guidance on identifying the character set (encoding) used by Syniverse SCG when sending SMS messages. Correctly identifying the character set helps avoid unnecessary message segmentation, especially when sending large SMS messages, and ensures optimal message length.

To avoid excessive segmentation and maximize SMS capacity, confirm your message uses the GSM-7 encoding, which allows for longer messages per segment.

Ensure Your Message Text is GSM-7

• GSM-7 encoding supports up to 160 characters per SMS segment. 

If your message contains non GSM-7 characters, the system will switch to UCS-2 encoding, reducing the segment capacity to 70 characters.

How to Check the Encoding Used by SCG

Option 1: SCG UI OUTBOX 

• Send the message you want to review as SMS to your own mobile number.
• In the SCG OUTBOX, double-click your message.
• Locate the encoding field value in the Fragments Info section. This field show the character encoding used by SCG.

Option 2: API Call

• Using Postman or your preferred API tool, Send the message you want to review as SMS to your own mobile number and keep the returned ID.
• Execute the following cURL command (replace <yourMessageId> with your actual message ID and add your authorization token): 

curl -L -X GET 'https://api.syniverse.com/scg-external-api/api/v1/messaging/messages?id=<yourMessageId>' -H 'Authorization: <your_token>' 

• In the returned JSON, look for the "encoding" field.
  • If you see "encoding": "GSM7BIT", your message uses the GSM-7 character set.
  • If you see "encoding": "UCS2", your message contains at least one non GSM-7 character.

Notes

- Some applications (including autocorrect features) may automatically change certain characters to non GSM-7, which can trigger UCS-2 encoding.

For example, different apostrophe styles can affect encoding:

"There’s a non GSM-7 character here"

"There isn’t a non GSM-7 character here"

- Any non GSM-7 character will cause your message to be sent as UCS-2, limiting each message body to 70 characters. If your message exceeds 70 characters in UCS-2, it will be split into fragments, each with a maximum of 67 characters (including the User Data Header).

- For additional information on message encoding refer to  Supported SMS Message & language Characters and Encoding

Always verify your message encoding before sending large SMS campaigns. Using GSM-7 ensures maximum efficiency and minimizes fragmentation.