# SMS Character Limit

The character limit for a single SMS message is 160 characters. However, most modern phones and networks support concatenation; they segment and rebuild messages up to 1600 characters. Messages not using [GSM-7](https://docs.localmail.io/messaging/learn-more-about-sms/what-is-gsm-7-character-encoding) encoding are limited to 70 characters.

### SMS Message Length and Character Encoding

When you send a SMS message over 160 characters, the message will be split. Large messages are segmented into 153 character segments and sent individually, then rebuilt by the recipient's device. For example, a 161-character message will be sent as two messages, one with 153 characters and the second with 8 characters.

If you include [non-GSM characters](https://docs.localmail.io/messaging/learn-more-about-sms/what-is-gsm-7-character-encoding), such as Chinese script, in SMS messages, those messages have to be sent via [UCS-2](https://docs.localmail.io/messaging/learn-more-about-sms/what-is-ucs-2-character-encoding) encoding. **Messages containing any UCS-2 characters are limited to 70 characters** and will be concatenated into 67 character message segments, even if the messages contain fewer than 160 characters.

### What is the history behind SMS message length? <a href="#what-is-the-history-behind-sms-message-length" id="what-is-the-history-behind-sms-message-length"></a>

*SMS* is a standardized communication protocol that enables devices to exchange short text messages and was defined as part of the [1985 GSM protocol](https://en.wikipedia.org/wiki/GSM_03.38). Originally, it was designed to "fit in between" existing signalling protocols, which is why SMS length is limited to 160 seven-bit characters. It was subsequently codified into the [SMPP signalling protocol](https://en.wikipedia.org/wiki/Short_Message_Peer-to-Peer) that transmits SMS and is limited to precisely 140 bytes (or 1120 bits).

But things get tricky because GSM-7, the original charater set designed for SMS, only has the ability to denote 128 different characters in those 7 bits. So if you want to include more Latin or non-Latin scripts, you'll need to use UCS-2.

A common mistake is to inadvertently use a UCS-2 character, thinking it's GSM-7 character. GSM-7 isn't a supported character set in many text editors. The classic mistake is to use "curly quotes" not realizing that they're part of UCS-2 and not GSM7.

We recommend that you check any mass messages in [our Message Segment calculator](https://localmail.github.io/message-segment-calculator/) before you send them out. It will flag any UCS-2 characters to avoid you being double-charged for messages. If you use Local mail, you can see whether a message was encoded as UCS-2 or GSM7 by viewing an individual message in your sms logs.

### Need More Help?

If you need any further Help During your Integration or questions related to technical know-how, you can reach out to our support team at **<support@localmail.io>**<br>