ption Calls toward CUCM destination-pattern 1... continues 204 SIP Trunking Example 10-3 continued voice-class codec 1 session target ipv4:172.x.x.x dtmf-relay - rtp-ni (3) Note the following: These commands enable CUBE's H.323-SIP interworking capability. 2. CUCM 4.2 requires an MTP for H.323 FastStart calls, which in turn is required for SIP Early-Offer calls toward the SP SIP Trunk. These statements define a collocated MTP on CUBE. 3. This command specifies RFC-2833 for H.323. The H.245 mechanisms can also be used, for example, dtmf-relay h245-signal. Sharing a SIP Trunk Across the Enterprise One of the many benefits of a border element is that it enables you to share a single SIP trunk among different CUCM and IP-PBXs at your site. It also enables you to connect to different vintages of these IP-PBXs using either the H.323 or SIP protocols. Figure 10-4 shows how to share a SIP Trunk across three CUCMs and two IP-PBXs at a site. SIP SP SIP Trunk Enterprise Demarc SIP or H.323 Figure 10-4 Sharing a SIP Trunk Across the Enterprise Chapter 10: Deployment Scenarios 205 Example 10-4 shows the additional configuration required to connect to the CUCMs and IP-PBXs shown in Figure 10-4. The SIP side facing the SP's network remains the same, as shown in Examples 10-1 and 10-2. Example 10-4 Sharing a SIP Trunk Across the Enterprise voice service voip address-hiding allow-connections h323 to sip allow-connections sip to h323 allow-connections sip to sip fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw h225 connect-passthru header-passing error-passthru midcall-signaling passthru g729 annexb all voice class codec 1 codec preference 1 g729br8 codec preference 2 g711ulaw interface GigabitEthernet010 description Inside towards CUCM ip address 172.x.x.x 255.255.255.0 duplex auto interface GigabitEthernet0/1 description Outside towards SIP Trunk ip address X.X.X.X 255.255.255.0 duplex auto dial-peer voice 701 voip description SP to CUCM - 1 with SIP destination-pattern 701 voice-class codec 1 sess