Message Segments:
What they are.
Why they matter.

SMS messages are made up of character batches called segments. But what exactly are message segments, and how do they affect our text costs?

SMS Message Segments

SMS Message Segments


What is an SMS Message Segment?

We all know what an SMS is, right? A short message of 160 characters or less (including spaces) that we can send from one mobile device to another.

But as with most things, it’s not quite that simple.

SMS messages are made up of segments. So what might seem like a single message to you could, in fact, be made up of several segments.

Why does that matter? Because the price you pay for your messages will depend upon the number of segments they use.

But what in tarnation is a message segment? And why do they affect our text costs?

Message segments


Message Segments Explained

Mobile phone carriers (AT&T, T-Mobile, Verizon, etc.) measure text messages in character batches called message segments. And they’ll charge you for sending text messages on a per-message segment basis.

Typically, a segment will consist of 160 characters, which is where our standard definition of a text message originates.


SMS Message Segments

But here’s the thing: The number of characters included in a text message can be more or less depending on two things:

1) The length of your message, and  2) The type of characters you use to create your message

Let’s take a look at this more closely.


SMS Message Length

While a standard text message can include up to 160 characters, you can send messages that are longer: up to 1280 characters, in fact. But the longer your message, the more you’ll be charged. That’s because carriers bill 160 characters as 1 message segment.

 Subsequent segments are charged for separately, though these additional segments can only contain up to 153 characters. Why? Because 7 characters are needed to decode, or recombine the multi-part messages (or segments) into a single message when they reach the recipient’s device.


SMS Character Types

SMS Message Segment

The letters, numbers, and symbols you use to write your messages will also impact how much you pay for them. That’s because they control how your messages are sent and received.

Carriers have to encode the characters into a format that can be transmitted over a network. But the encoding must also be converted back into its original form so the recipient can actually read your message.

But here it gets a bit more complicated.

The carriers encode graphic characters differently depending on their type. There are two main character classifications that carriers use:


SMS Message Segments and Message Segment


Classification 1

This consists of a standard alphabet comprising the most commonly used letters and symbols in different languages. These include:


GSM-7 character types

These characters are converted for transmission by the character encoding standard GSM-7: The most commonly used encoding type which is always supported on GSM networks.

The 7 refers to the fact that 7 bits are used to encode a single character. Since SMS messages are transmitted as 140 8-bit octets, a GSM-7 encoded message can contain up to 160 characters: (140 x 8) / 7 = 160.


Classification 2

Includes additional characters (e.g. emojis) and the letters, numbers, and symbols in different alphabets, such as Arabic, Chinese, and Korean.

The characters in this group are converted for transmission by the character encoding type UCS-2. This uses 16 bits (2 bytes) to encode a single character. Since SMS messages are transmitted as 140 8-bit octets, a UCS-2 message can contain up to 70 characters: (140 x 8) / (2 x 8) = 70.


But what does all this mean for you? It means that you now have all the information you need to keep your text costs down.


Simple Hacks to Keep Your Dollar Spend Low

SMS Message Segment GSM-7

If you include non-GSM-7 characters in your text (even a single emoji), your entire message will be encoded as UCS-2. In other words, you’ll be limited to just 70 characters per segment. With so few characters to play with, you’ll most likely exceed this limit quite quickly. The result? The carriers will bill you for two or more message segments when you thought you’d only written a single message.


Message Segment

So, to keep your message segments and thus your costs low, use standard GSM-7 characters in your messages.

Instead of including emojis (which we now know are UCS-2 characters), type them the old-fashioned way, using punctuation marks. That way, they’ll be classified as GSM-7 characters by the carriers and will not affect your segment total.


In addition, try to use abbreviations wherever possible to keep the length of your messages down. You can check out a handy list of abbreviations here. Also, where practicable, shorten words by replacing them with numbers.

For example, instead of the word <for>, use the number 4, or replace the word <to> with the number 2. Substitutions like these will quickly reduce the number of characters you use.  

A simple trick, maybe, but it’ll certainly help you to save your dollars. And let’s face it, why pay more than you have to?


SMS Message Segments

GSM-7 UCS-2 character types

Message Segments

About YakChat

Powering SMS for Microsoft 365, YakChat equips businesses to send/receive texts from personal and shared inboxes inside Microsoft Teams. Enabling secure Multi-Factor Authentication (MFA) across your team, and automated SMS workflows across your organization, YakChat extends the communication and collaboration power of Microsoft’s UC&C platform, unleashing maximum value for its users.


SMS Message Segments

YakChat powers SMS for Microsoft 365.YakChat equips businesses to send/receive texts from personal and shared inboxes inside Microsoft Teams. It also enables secure Multi-Factor Authentication (MFA) across your team. We also extend communication and collaboration power of Microsoft’s UC&C platform.

Message segment and SMS message segments will affect your costs. 


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