r. 22. This command is an example of how to configure T.38 fax on a per dial-peer basis, overriding the global configuration done earlier. 23. This is the dial-peer routing calls from AT&T to the enterprise CUCM. To route calls from CUBE to multiple CUCMs in the enterprise, create multiple dial-peers with the same configuration values, except set the session target to the alternate CUCMs. Calls can be routed to different clusters based on dial-plan (change the destination- pattern appropriately) or load-balanced across SIP trunk to different CUCM servers in the same cluster. 24. This command forces the configured NTE payload type value (in this case the 100 value) for incoming calls to CUCM. This command is used to synchronize RFC-2833 DTMF dynamic payload-type values with the various components in the AT&T net- work. The majority of the network components support this, but some older config- urations might still use other values such as 96. In cases where an incoming SIP INVITE from AT&T to CUCM carries a payload-type value other than 100, the CUBE command voice-class sip dtmf-relay force rtp-nte forces the configured pay- load-type under the dial-peer back to AT&T in the 200OK SDP message. This Chapter 10: Deployment Scenarios 197 enables the PSTN user to have the correct DTMF capability to navigate through auto-attendant or IVR services. 25. This command should be enabled when failover dial-peers are configured (for example, when using a CUCM cluster instead of a single CUCM IP address for all SIP calls). CUCM to a Verizon SIP Trunk Example 10-2 shows the CUBE configuration connecting to CUCM 6.1.2 on the inside and a Verizon SIP trunk on the outside. CUBE 1.2 (IOS 12.4(20)T) is used in this example. The following SIP trunk features were tested on this configuration: SIP trunk voice calls using G.729 codec Locating SIP servers using Domain Name Server (DNS) Service Location (SRV) and A records DTMF relay using RFC-2833 Fax using G.711 passthrough CUBE performing Delayed-Offer-to-Early-Offer conversion of the i