What's an SMS Part?

SMSes are sent in "parts", 1 SMS of a certain length could be 1 part, or multiple. Here we explain SMS parts to you.


Introduction

There are 2 ways to send SMS related to the way that individual characters or letters are formatted. This is called Character Encoding, and it can either be GSM-7 (we'll just call this GSM) or UCS-2 (Unicode).

If your message just contains text content, we're going to send it automatically for you as GSM so that you can get the best value for money.

SMS Parts do not mean that messages are sent separately, we will deliver (within reason) your SMS as a single message. The "SMS Part" is an implementation detail of how SMS works.


GSM Messages

A single GSM message is limited to 160 characters. If the length of your text goes over 160 characters, it becomes 2 parts, with each part limited to 153 characters.

For example, if you send one message that contains 160 characters, it will send as 1 SMS Part. However if it was 161 characters, it would be broken up in to 2 parts, with the first containing 153 characters and the second containing 8 characters.


UCS-2 Messages

If your message contains one or more Unicode characters (such as emojis Waving Hand) the character limit for your SMS is reduced to 70 characters. If the length of a UCS-2 message goes over 70 characters, each part is then limited to 67 characters.

Sending messages with emojis or other unicode characters can become extremely costly. We suggest using them sparingly, and have tools to force GSM only which will strip your UCS-2 characters (see  ⁠⁠Cost Saving⁠  ).

For example, if you send a message with an emoji that is 70 characters, it's sent as 1 SMS Part. However, if it was 71 characters, it would be broken up in to 2 parts, with the first containing 67 and the second containing 4 characters.


Tying it together

Here's another example for you, take this message:

Hi, this is Dave from Super Fast Autos! I'm ready to see you tomorrow.

That's 70 characters, it would be sent as a single SMS Part in either GSM or UCS-2 encoding.

Hello. This is Dave from Super Fast Autos! I'm ready to see you tomorrow.

This message is 73 characters, which is still sent as a single SMS Part in GSM encoding, which we would choose by default for this message anyway.

Waving Hand This is Dave from Super Fast Autos! I'm ready to see you tomorrow.

This message is 69 characters long, but because it contains an emoji, it's going to be sent as a UCS-2 message.

Hi Waving Hand This is Dave from Super Fast Autos! I'm ready to see you tomorrow.

This message at just 72 characters will send in 2 parts in UCS-2 encoding.


Any questions?

We hope SMS parts make sense to you now, but feel free to get in touch if you need any further guidance.