GSM Network Interfaces connect between different elements in the 2G (GSM) mobile communication network, which is based on the SS7 protocol stack. The connection between the GPRS system and the GSM core network (NSS) also uses the SS7 protocol.
In the following table, you will find a list of interfaces and the network elements they are used to connect between elements in the GSM Mobile Network:
GSM Interfaces
| Interface | Network location | |
|---|---|---|
| A interface | Between the BSS and the MSC | |
| Abis interface | An internal interface in the BSS (base station). Links between the BSC and BTS. Enables control of the radio frequency allocation in the BTS | |
| B interface | Between the MSC and the VLR. Many MSCs have an included VLR, in which case B is an “internal” interface | |
| C interface | Used in connections between the the HLR and the MSC, and between the HLR and the GMSC / SMS Gateway | |
| D interface | Between the MSC / VLR and the HLR. Used for subscriber management and transferring handset Location Update | |
| E interface | Used for Inter-MSC handover, in case there is more than one MSC in the network | |
| F interface | Between the MSC and the EIR. Used for Equipment (IMEI) identity check for network access | |
| G interface | Connects between two VLRs that are each in a different MSC, for transferring subscriber information | |
| H interface | Between the MSC and the SMS Gateway. Used for transmitting SMS over the circuit switched network | |
| I interface | Between the MSC and handsets in the network. Messages exchanged over the I interface are relayed transparently through the BSS | |
| J interface | Handles messages between theHLR and the gsmSCF | |
| Um interface | The radio network interface standard that is used for communication between mobile devices (ME/handsets) and a network base station (BTS/BSC) | |
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Sources: MAP (Wikipedia), Radio Electronics |
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GPRS Interfaces to the GSM NSS
| Interface | Network location | |
|---|---|---|
| Ga interface | Between GSNs and the Charging Gateway inside the same PLMN (Public Land Mobile Network) | |
| Gb interface | Between the SGSN and BSS | |
| Gc interface | Between the GGSN and the HLR | |
| Gd interface | Between the SMS-GMSC and the SGSN | |
| Ge interface | Between the SGSN and the SCP. Uses the CAP protocol | |
| Gf interface | Between an SGSN and an EIR | |
| Gi interface | IP based interface between the GGSN and a public data network (PDN) either directly to the Internet or through a WAP gateway. | |
| Gmb interface | Between the GGSN and the BM-SC | |
| Gn interface | Between two GSNs in the same PLMN | |
| Gp interface | Between two GSNs in different PLMNs | |
| Gr interface | Between the SGSN and the HLR | |
| Gs interface | Between the SGSN and the MSC/VLR | |
| Lg interface | Between the SGSN and the GMLC, used for location services | |
|
Partial Source: GPRS Core Network (Wikipedia) |
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