Since their iOS 11 update, Apple has auto-enabled a feature called Smart Punctuation. Smart Punctuation is a feature that substitutes some forms of punctuation with those that are more typographically acceptable. The Smart Punctuation characters use Unicode encoding. When you send a Unicode message it is segmented per every 70 characters as opposed to GSM which is segmented per every 160 characters. Read more about how you are billed for long messages.
If your message has any special characters (Smart Punctuation) or emojis (aka non-GSM characters), this forces the carriers to use a different encoding which will reduce the segment size of SMS messages to 70 characters.
There are steps you can take to prevent this from happening on your account.
Here are the steps to disabling Smart Punctuation on your iOS device:
- Go to the settings app
- Go to the “General” settings
- Go to the “Keyboard” settings
- Disable “Smart Punctuation”