... IPPBX from worldwide vendors, including IP-PBX from Microsoft (OCS), Cisco (CallManager), Nortel (CS1000), and softswitch from Huawei, ZTE, Ericson, and ... .30, T.38 fax relayDTMFRFC 2833, SIP INFO, Transparent audioBillingRADIUS Interface; Polarity ReverseUser FeatureCaller ID, Call forward, Call transfer, Call fork ...