 trunk Connecting CUCM using SIP to a Verizon SIP trunk Connecting CUCM using H.323 to a SIP trunk Connecting multiple Internet Protocol Private Branch Exchanges (IP-PBX) in the enterprise using H.323 and SIP to a shared SIP trunk Connecting a contact center to a SIP trunk Cisco UCM SIP to an AT&T FlexReach SIP Trunk When using CUCM 6.0 or later, the use of SIP (rather than H.323) is recommended to interconnect to a SP SIP trunk, as shown in Figure 10-2. Example 10-1 shows the Cisco Unified Border Element (CUBE) configuration connecting to CUCM 7.0 on the inside and an AT&T FlexReach SIP trunk on the outside. CUBE 1.2 Internet Operation System (IOS) 12.4(22)T is used in this example. The following SIP trunk features were tested on this configuration: Chapter 10: Deployment Scenarios 193 Enterprise CUCM 6.x or 7.x SIP (UDP) (TCP or UDP) Figure 10-2 CUCM to SIP Trunk Interconnect Using SIP SIP trunk voice calls using G.729 codec Calling name display Intrasite call transfer Call hold and resume Call forward all, call forward busy, and call forward no answer Dual-tone multi-frequency (DTMF) relay using Request for Comments (RFC) 2833 Fax using T.38 or G.711 passthrough CUBE performing Delayed-Offer-to-Early-Offer conversion of the initial SIP INVITE Example 10-1 Cisco UCM SIP to CUBE to an AT&T FlexReach SIP Trunk voice-card 0 (1) dspfarm dsp services dspfarm voice service voip address-hiding (2) allow-connections - sip to sip (3) redirect ip2ip fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw (4) header - passing error -passthru - (5) midcall - signaling passthru g729 annexb all (7) voice class codec 1 (8) codec preference 1 g729r8 codec preference 2 g711ulaw continues 194 SIP Trunking Example 10-1 continued voice class sip-profiles 1 request INVITE sip-header Diversion modify "<sip:(.*)@(.*)>' II <sip:732320\1@\2> (9) interface GigabitEthernet010 (10) description Inside towards CUCM ip address 172.X.X.X 255.255.255.0 duplex auto interface GigabitEthernet0/1 (11) description Outside to