my query is, in case of GSM, we have Ater interface between BSC to transcoder and A-interface between Transcoder to MSC. Now, for each Ater there will be 4 corresponding A-links, carrying 120 erlangs (30 erlang for each A-link). my question is , what will be the Erlang for Ater-interface? will it be 30 Erlang or will it be 120 Erlang? plz suggest.