SCCP does not provide any connection identifiers to BSSAP. On the contrary the application part (i.e. BSSAP)must provide Source Local Reference to SCCP by means of SCCP-primitives (e.g. N-CONNECT_request primitive) on interface between BSSAP and SCCP. You can see more details about SCCP and its primitives in 711 Recommendation of ITU-T.
With best Regard, Pan