SMS Encoding

IntelePeer supports two main types of encoding, which are dynamically switched based on the characters you enter in the message text:

  • GSM-7
  • A standard alphabet for SMS messages containing the most commonly used letters and symbols.
  • 7 bits are used to send a single character with GSM-7 encoding. Since SMS messages are transmitted as 140 8-bit octets, a message encoded with GSM-7 can contain up to 160 characters: (140*8)/7 = 160.
  • If concatenated messages are used, a User Data Header of 6 bytes is used so the receiving device can re-assemble the messages. This leaves 153 GSM-7 characters available per single SMS message segment.
  • UCS-2
  • An expanded alphabet for SMS messages containing additional characters and alphabets (i.e., Korean, Chinese, Arabic, etc.).
  • 16 bits (2 bytes) are used to send a single character with UCS-2 encoding. Since SMS messages are transmitted as 140 8-bit octets, a message encoded with UCS-2 can contain up to 70 characters: (140*8)/(2*8) = 70.
  • If concatenated messages are used, a User Data Header of 6 bytes is used so the receiving device can re-assemble the messages. This leaves 67 UCS-2 characters available per single SMS message segment.

Using this simple tool, you can check the following:

  • Which encoding type will be used for your message
  • The number of characters in your message
  • How many segments your message will be split into

Here are some tips and tricks to keep your SMS short and keep cost down:

  • Make sure you use only the following GSM-7 characters instead of UCS-2 characters:
@£$¥èéùìòÇ`Øø`ÅåΔ_ΦΓΛΩΠΨΣΘΞ`ÆæßÉ!"#¤%&'()*=,-./0123456789:;<=>?¡ABCDEFGHIJKLMNOPQRSTUVWXYZÄÖÑÜ`¿abcdefghijklmnopqrstuvwxyzäöñüà
  • Use the old-fashioned : ) or ; ) instead of 😊 or 😉 emojis, which are UCS-2 characters
  • Use abbreviations and try to shorten words (i.e., 2gether vs together, or 4ever vs forever)