SIP Carrier 2 IX78 ADSL SIP FW CDR (MOS) QoS IP-Centrex – First phase Billing / User db ITSP Servers SIP Carrier 1 Ingate SBC Firewall Internet FENT CDR (MOS) Max 2000 calls PC Softphone Legacy Firewall PC Softphone Simple NAT/FW The Ingate SBC Firewall, centrally located at the ITSP, will provide protection of the network, routing and interoperability with carriers and IP-PBX as well Far End NAT Traversal (FENT). Ingate SIParator CDR (MOS) QoS Some customers might have advanced firewalls. An Ingate SIParator will then be required for SIP-based communication to traverse the firewall. QoS being so important for good quality and the MOS score giving a valuable assessment of the quality, some ITSPs standardise and always install an Ingate or an IX78 as CPE. Avaya CM Avaya Environment Avaya Environment