There are many operating systems used in mobile phones. Here are some popular operating systems for phones:

Android:
Developed by Google.
It is widely used in most Android phones.
It is considered open source, which means developers can modify and adapt it.

iOS:
Developed by Apple.
Only used in iPhones and some tablets and digital players.

HarmonyOS:
Developed by Huawei.
It is designed to provide an integrated experience for users across a variety of devices, including phones, tablets and smart devices.

KaiOS:
A lightweight operating system targeting mobile phones with low specifications.
It is used in affordable smartphones and supports specific applications such as WhatsApp and YouTube.

Tizen:
Developed by the Tizen Committee, which includes Samsung, Intel and the Linux Committee.
It is used in some Samsung smart devices and other devices.

BlackBerry:
It is used in BlackBerry smartphones.
It focuses on security and encryption, and was mainly used in business-targeted devices.

Windows Phone:
Developed by Microsoft.
Its development and support was officially discontinued in 2017.

Please note that the status of the systems mentioned may have changed over time, and new systems or updates to existing systems may have been released.