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Within the BSS Adax provides the Gb interface. The Gb Interface provides the interconnection between the BSS and the SGSN. Within the Gb Interface protocol stack, the Network Service (NS) entity provides network service primitives that allow the transmission and reception of upper layer protocol data units between the BSS and SGSN. NS runs over Adax Frame Relay.

Large numbers of BSS to SGSN connections need to be supported within the GPRS network. As a result, multiple Frame Relay channels are required per SGSN for the NS. These are 64k signaling connections over T1/E1 lines and multiple connections can also be back-hauled via an intermediate Frame Relay network over OC3/STM-1 to the SGSN.

Adax can support 2,048 Frame Relay channels and 10,000 DLCIs per system, enabling large numbers of BSSs to be connected to a single SGSN. Signaling and User Plane Content can also be run over the same links. As the system grows, the interface between the Adax Frame Relay software and the NS will remain the same, as will the interface between the Gb Interface stack and the application. Consequently additional Adax cards can be added at a future stage without any changes to the software interface, and vendor investment in the application development is preserved.

The above is supported via the Adax ACT card, which offers one of the highest port densities in the industry, providing up to 256 DSO connections over 8 T1/E1 links per slot, and multiple cards in a system can deliver up to 2,048 links. For vendors who also want to run SS7 MTP2 for connection from the SGSN over the Gs Interface, on the same card as the Frame Relay for the Gb Interface, the Adax HDC multiple protocol card can be used. This high-density controller card provides up to 128 channels of multiple protocols over 4 T1/E1 connections. The ACT and HDC cards also have two 10/100 BaseT Ethernet ports for connection to the IP networks.