The GPRS Packet Control Unit is co-located with the GSM BTS or GSM BSC in order to provide packet-switched services for 2G (2.5G, 2.75G) networks. OsmoPCU is the Osmcoom implementation of this network element. It interfaces to osmo-bts via the PCU socket of OsmoBTS and via Gb (NS-over-IP) interface with the SGSN such as OsmoSGSN.