ITU-T Recommendations

This Recommendation defines a V-interface (V5.1) for the connection of an Access Network (AN) to a Local Exchange (LE) for the support of the following access types:
– analogue telephone access;
– ISDN basic access with a NT1 separate from the AN or integrated in the AN, based on Recommen-dations G.960 and I.430;
– other analogue or digital accesses for semi-permanent connections without associated outband signalling information, with flexible (provisioned) information channel (bearer channel) allocation but without concentration capability within the AN.
The electrical and functional interface specification uses the 2048 kbit/s parts of Recommendations G.703, G.704 and G.706.
The signalling from the PSTN user port is converted into a stimulus protocol with a functional part for the signalling path using layer 3 multiplexing for the information from the different user ports.
The information from the ISDN D-channels is frame relayed in the Access Network using the mechanisms defined in Recommendation Q.922.
A control protocol defined in this Recommendation is used for the exchange of the individual port status and control functions required for the coordination with the call control procedures in the Local Exchange.
In order to coordinate the traffic demands in the various protocols, 1, 2 or 3 communication channels can be provisioned to transport the various protocols and frame relayed information. The data link layer for the protocols is defined on the basis of Recommendations Q.920 and Q.921.
Interface V5.1 is upgradable to V5.2 through re-provisioning and by implementation of the additional functionality.