> For the complete documentation index, see [llms.txt](https://gsm-hacking.telco-sec.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm-hacking.telco-sec.com/bts-to-mobile-station/intro.md).

# Intro

### GSM Radio Stack

The GSM Radio Stack comprises multiple layers, each responsible for different communication aspects in GSM mobile networks:

1. **Physical Layer (Layer 1)**: Manages the actual radio transmission and reception.
2. **Data Link Layer (Layer 2)**: Includes protocols like LAPDm, responsible for error correction and reliable data transfer.
3. **Network Layer (Layer 3)**: Consists of sub-layers for call control, mobility management, and radio resource management.

![](/files/UkncANO64M6Uui4zi9uO)

This layered approach ensures efficient management and operation of GSM mobile communications.