prENV 50XXX

Signalling between ISPBX and Public Networks - 1) Application of layer 2 sign. Prot. at the T ref. pt. (point-to-point) 2) Application of layer 3 sign. prot. at the T ref. pt., B. call, circt Sw (point-to-point) 3) Generic procedures for the control of suppl. services at the T ref. pt. 4) Suppl. Services sign. prot. at the T ref. pt.