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How Flowio encodes my text messages?
How Flowio encodes my text messages?

Understand the technical aspect of how Flowio encodes SMS messages

Flowio Support avatar
Written by Flowio Support
Updated over a week ago

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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