hat matches these criteria. 5. This section of commands defines the dpi_policy FW policy, which does rate limit- ing on SIP traffic defined in the sip_rfc3261 class, and SIP inspection on the traffic defined in the sip_rfc3261_2 class. This section of commands defines the sip-policy-inbound FW policy, which inspects the SIP traffic that matches the SIP-inbound class and drops all other non- matching traffic. This section of commands defines the ZBFW zones and inspection policies. Whenever traffic flows between the zones, the applicable inspection policy is exe- cuted on the traffic. In this example, the sip-policy-inbound policy is used for traf- fic in all directions. You could also define different policies for the different direc- tions of traffic. The interface facing the inside of the network is assigned to the zin zone. The interface facing the outside of the network is assigned to the zout zone. 10. The remainder of the typical CUBE configuration (dial-peers) follows here. CUBE with Tcl Scripting Tcl scripting is a general Cisco IOS unified communication (UC) capability that provides powerful means of intercepting, manipulating, controlling call routing, treatment, and information associated with calls. Tcl scripts are generally attached to dial-peers SO that any application using dial-peers (such as CUBE) can be customized by using Tcl scripts. Example 10-11 provides a configuration segment where a Tcl script was used to deter- mine if a call is audio only or video and audio and have CUBE send the appropriate Session Description Protocol (SDP) for the call that arrives at CUBE without an SDP alto- gether. The steps in the example are as follows: CUCM sends a Delayed Offer (without an SDP) SIP INVITE toward CUBE using the SIP CONTACT header (as per RFC 3840) to indicate endpoint video capability. CUBE converts the Delayed Offer INVITE into an Early Offer (requiring an SDP). The Tcl script on CUBE examines the original INVITE for video capabilities in the CONTACT header, and if present, the outgoing Early O