Samsung
Change SMS Input Mode (GSM or Unicode) auf Samsung
Text messages are still sent using an old character standard called GSM alphabet. It only covers basic Latin letters, numbers and a few symbols. As soon as you add an emoji or a character outside that set, your phone has to switch the whole message to Unicode encoding, which uses more space per character and often splits one text into several parts.
The Input mode setting on Samsung phones controls how this switch happens. Set to GSM alphabet, the phone strips or blocks unsupported characters instead of switching encoding. Set to Unicode, every message uses the wider character set regardless of content, which avoids missing symbols but can increase message count. Automatic lets the phone choose the encoding based on what you actually type, which is the setting most people want.
To change it, open Tap on Messages ➔ Open the Menu ➔ Tap on Settings ➔ Tap on More settings ➔ Tap on Text messages ➔ Tap on Input mode ➔ Choose GSM alphabet, Unicode or Automatic.
If your carrier charges per message part, check how Automatic affects your usual conversations before leaving it on permanently.