IP-Centrex – First phase Max 2000 calls IX78 ADSL SIP FW CDR (MOS) QoS 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. SIP Carrier 2 SIP Carrier 1 Avaya Environment Internet PC Softphone Ingate SIParator CDR (MOS) QoS Simple NAT/FW PC Softphone Legacy Firewall 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). Avaya Environment 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). Potential customers of an IP-Centrex Service Provider will usually have networks protected NAT/simple firewalls. The FENT function will take care of NAT issues. Some 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. Some customers might have advanced firewalls. An Ingate SIParator will then be required for SIP-based communication to traverse the firewall. FENT CDR (MOS) Ingate SBC Firewall ITSP Servers Avaya CM Billing / User db

IP-Centrex – Next phase Max 3x2000 calls (in this example) IX78 ADSL SIP FW CDR (MOS) QoS SIP Carrier 1 SIP Carrier 2 Avaya Environment Avaya Environment Internet PC Softphone Simple NAT/FW PC Softphone Ingate SIParator Legacy Firewall CDR (MOS) QoS As the number of customers grow, capacity requirement increases. A battery of Ingates can be built with load balancing between them achieved on basis of DNS SRV. Servers DNS SRV load balancing As the number of customers grow, capacity requirement increases. A battery of Ingates can be built with load balancing between them achieved on basis of DNS SRV. Avaya CM CDR (MOS) ITSP Ingate SBC Firewall Billing / User db

Reference Case GCM - A Service Provider offering Hosted VoIP services, with Ingate and Avaya equipment