> For the complete documentation index, see [llms.txt](https://gsm.learn-telecom.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm.learn-telecom.com/gsm-interfaces.md).

# GSM Interfaces

- [A interface](https://gsm.learn-telecom.com/gsm-interfaces/a-interface.md)
- [A-ter interface](https://gsm.learn-telecom.com/gsm-interfaces/a-ter-interface.md)
- [A-bis interface](https://gsm.learn-telecom.com/gsm-interfaces/a-bis-interface.md)
- [Um interface](https://gsm.learn-telecom.com/gsm-interfaces/um-interface.md)