... realy 1 to 4 E1/T1 ports VoIP SIP E1/T1 ISDN PRI Trunk gateway Support PRI and SIPT.38 Fax RelayRouting ... ,GSM,iLBC,T.38)Ideal PSTN termination for IP phones, VoIP gateway, IPPBX, PBX accessEmbeded with RTP voice proxy, Digits translationAuto Dial ... , Performance DataSignaling· PSTN Side ISDN PRI Standard: ANSI, NI-2, DMS, 5ESS· VoIP ProtocolSIP (RFC3261) , 2976 Info Method, 3515 Refer Method, 3581 ...