Why have I been charged twice for sending one message?


tyntec charges per SMS we send for you, not per API call. This means that if your message is longer than 160 characters, the character limit for an SMS, you will be charged for two messages (or more). It is possible to send multiple SMS together, formed as a single, longer SMS; this considered being a concatenated SMS. Even as the recipient sees the message as one, tyntec will charge you for each of these messages individually (the same way as our suppliers charge tyntec).

Also, be aware that if you are sending SMS in Unicode, your character count per SMS will be 70 characters for a one-part message, due to the fact that each UCS2 character requires 2 bytes. The 7-byte header for concatenated messages will also apply when sending in excess of one message. As a result, a two-part Unicode message has a limit of 134 characters and a three-part Unicode message has a limit of 201 characters.

The maximum number of characters per single message depends on the encoding; for example:

  • 160 characters for 7-bit encoding (e.g. latin-1/9 and GSM8)
  • 140 characters for 8-bit encoding (binary)
  • 70 characters for 16-bit encoding (Unicode)

The maximum number of characters per concatenated message is slightly reduced due to the inclusion of concatenation headers; for example:

  • 152 characters for 7-bit encoding (e.g. latin-1/9 and GSM8)
  • 133 characters for 8-bit encoding (binary)
  • 66 characters for 16-bit encoding (Unicode)

Please see our SMS API documentation for more information.