As SMS messages are transmitted 140 8-bit octets at a time, we'll automatically use the most compact encoding possible - which is GSM-7 characters when you send text messages with Flowio.

What is GSM-7 encoding?

GSM-7 is a character encoding standard which packs the most commonly used letters and symbols in many languages into 7 bits each for usage on GSM networks. It can carry up to 160 characters.

If you include any non GSM-7 characters in your message body, we will fall back to UCS-2 encoding - which will limit your message bodies to 70 characters each.

How do I check if my messages are encoded in GSM-7?

Check this page and enter your text body to see if it's possible for the message to be encoded in GSM-7, and if UCS-2 is needed.

What if I enter a message body of more than 160 characters?

If you enter a message body exceeds 160 GSM-7 characters or 70 UCS-2 characters - we will split the message into multiple segments.

On the other hand, a User Data Header of six (6) Bytes is also prepended to instruct the recipient's device on how to re-assemble the messages. For multi-segment messages, this leaves 153 GSM-7 characters or 67 UCS-2 characters per segment.

Please note that this can cause the total number of messages in a campaign to be sent more than you expect. For example, a message body of 152 GSM-7-compatible characters and a single unicode character (such as emoticons) will be split into 3 messages. For the reason that the unicode character changes the encoding into UCS-2. And eventually, you might be charged for 3 outgoing messages.

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