What's the use of an old mobile phone?

Old mobile phones have many uses, such as 1. Spare mobile phone: used in case of problems with the original mobile phone. 2. Alarm clock, timer and reminder: Set reminder and management time. 3. Media player: used to listen to music, watch videos and view photos. 4. E-book reader: download e-book applications and read e-books. 5. Game equipment: download games for entertainment and leisure. 6. Learning tools: Install learning applications, such as dictionaries and online courses. 7. Fitness Assistant: Use pedometer and fitness application to record exercise data. 8. Remote control: Turn the mobile phone into a smart home remote control. 9. Navigation equipment: Use the map application to navigate. 10. Donate or recycle: donate old mobile phones to people in need or recycle them.