SIP Trunking & Carrier Connections

Book excerpt: SIP Trunking & Carrier Connections This module is all about connecting to carriers to communicate VoIP phone calls, both carrier-to-carrier connections and business-to-carrier SIP trunking. You'll learn how competitive carriers terminate VoIP phone calls on Local Exchange Carriers using the switched access tariff and tandem access trunks. We'll understand why this will be a native VoIP connection in the future, and the role of Session Border Controllers. Then we'll understand how a business system can connect its locations and to the PSTN using SIP Trunking services, and the advantage over the legacy ISDN PRI PBX trunks. VoIP Module 5 Detailed Outline 5. SIP Trunking and Carrier Connections 5.1 Carrier-to-Carrier Connection via Tandem Access Trunks ...... 5.1.1 Internet VSP to LEC ...... 5.1.2 Generalized Carrier-Carrier Example ...... 5.1.3 Competitive Long-Distance 5.2 Carrier-to-Carrier VoIP Interconnection ...... 5.2.1 Native VoIP Interconnect ...... 5.2.2 Issues to Resolve 5.3 Session Border Controllers ...... 5.3.1 MPLS Core ...... 5.3.2 SIP Trunking ...... 5.3.3 Security, Lawful Intercept and Call Routing ...... 5.3.4 Spam Filtering 5.4 PBX Trunks and Gateways ...... 5.4.1 Business Phone System – PSTN Connectivity ...... 5.4.2 Legacy PBXs and PBX Trunks ...... 5.4.3 Replacing the PBX with a Softswitch ...... 5.4.4 Using a Gateway ...... 5.4.5 Intelligent Gateway Invisible to the Softswitch 5.5 Megaco: Softswitch Controlling the Gateway ...... 5.5.1 Non-Intelligent Gateway ...... 5.5.2 Softswitch Tells The Gateway What to Do ...... 5.5.3 Media Gateway Control Protocol (Megaco) 5.6 SIP Trunking ...... 5.6.1 PBX Trunk Replacement ...... 5.6.2 Advantages ...... 5.6.3 Challenges