> 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/a-bis-interface.md).

# A-bis interface

A-bis interface connects BSC to BTS by cable or microwave links.

Type of Data:

1. User Information
2. Signalling Information
3. Synchronization data
4. O\&M alarms

### TRX 

Signalling between BSC and BTS

(TRansceiver) is the device responsible for transmitting and receiving radio signals between the BTS and the mobile devices. 

Each TRX handles multiple channels and is crucial for maintaining communication in a mobile network.