SMS Character Encoding and Charging

1. SMS Content with GSM-7 Characters

If your SMS content contains only GSM-7 characters:

  • Standard SMS: 160 characters per charging unit.
  • After adding a signature, if the total exceeds 160 characters, the message is charged per 154 characters (concatenated SMS).
  • Character counting rules:
    • GSM-7 basic characters: 1 character each
    • GSM-7 extension characters: 2 characters each

2. SMS Content with Non-GSM-7 Characters

If your SMS content contains non-GSM-7 characters (e.g., Chinese, Japanese):

  • Standard SMS: 70 characters per charging unit.

3. GSM-7 Encoding Standard

GSM-7 is a character encoding standard that packs the most commonly used letters and symbols in many languages into 7 bits each for usage on GSM networks. Since SMS messages are transmitted in 140 8-bit octets, GSM-7 encoded SMS messages can carry up to 160 characters.

Reference: GSM 03.38 Standard

4. Special Considerations for Malaysia (Country Code: +60)

  • Mobile operators require the content header RM 0.00 to be added to every message sent to Malaysia.
  • This header informs the recipient that they were not charged for receiving the SMS.
  • Sending messages without this header may result in:
    • Content truncation
    • Message delivery failure
  • Concatenated messages are supported by all mobile operators except Digi Malaysia, which delivers them as multiple separate messages.