> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sendo.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Segments

> What are SMS/MMS message segments?

#### SMS segments

SMS messages are sent in **160 character** (140 byte) chunks known as message segments. Each SMS message you send will be billed based on the number of segments it contains. If a message is longer than the maximum number of characters allowed in a single segment, it will be split into multiple segments and reassembled on the receiving device as a single message. The `numSegments` field will tell you how many segments were used.

When you send multi-segment SMS messages, we must attach a data header to each message that tells the destination how to reassemble it. This takes up 6 bytes, leaving 153 characters for standard GSM-7 encoded messages. If the message contains any <Tooltip tip="Includes emoji and other special characters like ❝ ⦅ ✥ ＞ Ａ">UCS-2 symbols</Tooltip>, each message segment can only fit 67 characters (see below).

<Tip>**Note:** Sendo now converts common UCS-2 symbols to their GSM-7 equivalent</Tip>

#### MMS segments

Every MMS message, regardless of size, will always be counted as one segment. The maximum length of the message body must be less than 1500 characters.

### Special characters

If you include <Tooltip tip="Includes emoji and other special characters like ❝ ⦅ ✥ ＞ Ａ">special characters</Tooltip> like emoji in your SMS message body, we must use Unicode (UCS2) encoding to send the message. This means all characters are encoded using 16 bits, instead of 8 bits. Because of this, each segment can only contain 67 characters instead of 153. So, you may notice that messages that contain emoji or other symbols are billed at a higher rate. The `numSegments` field will tell you how many segments were used.

#### Auto encoding

Sendo has a feature that detects common Unicode symbols and replaces them with their GSM-7 equivalent. This means that if your message contains a UCS-2 symbol like `‘` or `—`, we will convert them to `'` and `-` respectively. This will allow your message to be sent using the more efficient GSM-7 encoding, using fewer message segments and saving you money. This is enabled by default, but can be turned off by [contacting us](mailto:support@sendo.dev).

<Note>**Note:** Emoji do not have a GSM-7 equivalent, so they will always be sent using UCS-2</Note>

Some <Tooltip tip="Please contact us for a full list">common characters</Tooltip> that are converted include:

| UCS-2 character | Glyph | Converted |
| --------------- | ----- | --------- |
| U+201C          | `“`   | `"`       |
| U+201D          | `”`   | `"`       |
| U+2018          | `‘`   | `'`       |
| U+2014          | `—`   | `-`       |
| U+2026          | `…`   | `...`     |
| U+FF3F          | `＿`   | `_`       |
| U+00BD          | `½`   | `1/2`     |
| U+2022          | `•`   | `-`       |
| U+00F7          | `÷`   | `/`       |