This page of GSM tutorial covers GSM network interfaces which includes Um, A, Asub, Abis, B, C, D, E, F and G interfaces.
Figure-1 depicts all the GSM network interfaces between GSM subsystems. The table below describes the same GSM network interfaces.
| GSM interface | Description with position |
|---|---|
| Um | It is the air interface used between MS and BTS.It carries the GSM bursts carrying data and control information. Also referred as Air interface. |
| A or Asub | It is used between BSC and MSC/VLR. It supports 2Mbps standard digital connection as per CCITT. |
| Abis | It is used between BTS and BSC. It supports two types of communication links viz. traffic channel at 64 kbps and signaling channel at 16 kbps. |
| B | It is used between MSC and VLR. |
| C | It is used between HLR and GMSC. Also between MSC and HLR. |
| D | It is used between HLR and VLR. |
| E | It is used between MSC and another MSC or G-MSC. |
| F | It is used between EIR and MSC and between EIR and G-MSC. |
| G | It is used between VLR and another VLR. |
