== A-link including SCCP/BSSAP/DTAP

OsmoBSC implements a minimal sub-set of the GSM A interface as specified
in TS 08.08.

Unlike classic A interface implementations for E1 interfaces, OsmoBSC
implements a variant of encapsulating the A interface over IP.  To do
so, the SCCP messages are wrapped in an IPA multiplex and then
communicated over TCP.  The audio channels are mapped to RTP streams.

This protocol stacking is sometimes called "SCCPlite".

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