with SDP). This implies the H.323 side must be H.323 Fast Start. For Company P, CUCM must be configured inbound and outbound H.323 Fast Start, which requires the use of an MTP. MTP is a co-resident on the same router. PVDM2-64 Digital Signal Processor (DSP) is used to facilitate MTP resources. A side effect for using Early Offer (MTP) is that IVR Greetings are played instantly; no waiting for the far end to finish setup for the RTP media path. 500 ms delay is introduced at the initial prompt Welcome to Meeting. CUBEs are over-provisioned with MTP resources for redundancy. Example 12-3 shows the configuration in the CUBE that ensures the interworking between H.323 and SIP network. Chapter 12: Case Studies 271 Example 12-3 H.323-SIP Interworking Configuration voice service voip no notify redirect ip2ip <<< Needed for SIP LoadBalancer allow-connections h323 to sip <<< Calls from Company - P to Q allow-connections sip to h323 <<< Calls from Company Q to P redirect ip2ip <<<< Allows redirects w/o drops ip circuit max-calls 500 <<<< Loop protection H323 ip circuit default only redirect contact order best-match - <<< Needed to pass extra Session Digits DTMF Interworking Dual-Tone Multi-Frequency (DTMF) plays an important role in the IVR system. Company Q's conferencing server does not have speech recognition technology. You need to press the meeting number from your telephone key pad to join a specific meet- ing. When we have multiple call-legs in a single conversation, DTMF code does not flow end to end. It hops call-leg to call-leg. So, if the DTMF does not work in any of the call- legs, the pressed digits will never reach the destination. Different methods exist to carry DTMF digits. You can set up in-band or out-of-band techniques to pass DTMF. Moreover, H.323 and SIP have their own implementations to transmit DTMF codes. So, to make the DTMF interworking between two different net- works, the appropriate DTMF type must be configured at the incoming and outgoing dial-peers. Company Q's backend systems use RFC-2388 (N