Character Encoding, Restrictions

The input settings of your computer will have an effect on the character encoding, and as a result the number of characters you can include in a single text message. We currently support GSM encoding 03.38 (standard and extended). Anything else will automatically be converted to UTF-16 encoding.

The different encoding types result in the different character limits because of the size of the individual characters in the message: Latin1 characters are 1-byte characters, whereas UTF-16 are 2-byte characters.

Note: With GSM encoding there are exceptions called Extended Characters which are 2-byte characters, including: ( , ~ , ^ , } , { , | , > , <. These might not display correctly due to limitations on the recipient’s device.

Sending Long messages: SMS Concatenation

To help compensate for the limited characters per SMS, some mobile phones and networks support SMS Concatenation. This is where extra-long SMS message content is split into multiple messages when it is sent, and is then recombined into a single message by the recipient device. To the recipient it looks like one long SMS, and the concatenation is nearly transparent, with the exception that each message is billed separately.

If an SMS is sent with 240 characters (GSM encoding) then it will be processed as two separate messages, and billed accordingly. Please note: not all network operators support this feature. If you do plan to use it, please check with Emarsys Support first.

GSM encoding:

  • One standard SMS message = 160 characters (max)
  • Two concatenated SMS messages = 306 characters (max)

UTF-16 encoding:

  • One standard SMS message = 70 characters (max)
  • Two concatenated SMS messages = 134 characters (max)

Although we do support concatenation, we do not recommend using it as not all providers fully support this technology, resulting in the content potentially not being correctly rendered. If you still wish to use it, we recommend that you first discuss this with Emarsys Support.