ed) on the border element. The other leg of the call has no signaling or media encryption. Both legs TLS; one leg media encryption (e): The signaling of both legs of the call is encrypted with TLS and is terminated on the border element. The media of one leg is encrypted with SRTP and terminated (that is, decrypted) on the border element. The other leg of the call has media encryption. Summary This chapter along with Chapter 7 focused on key areas of network design considerations you should work through while planning or installing a SIP trunk for production purposes in your network. This chapter elaborated specifically on interworking and interoperability areas for SIP trunking. H.323 and SIP interworking and ways to normalize SIP messaging to aid interworking of applications speaking, or preferring, different dialects of SIP is discussed. Interworking in the media path including different DTMF relay methods; different codecs and different fax methods are also covered. Completing the discussion is information on signaling and media encryption methods and ways to interwork encrypted and nonencrypted network segments. Chapter 9, "Questions to Ask of a Service Provider Offering and SBC Vendor," shifts the focus to areas to explore with your service provider when looking for a SIP trunk service and guides you on how to evaluate different offerings. Further Reading The following documents and references provide additional information on the topics covered in this chapter. CUBE Documents Examples on SIP Normalization configuration for the CUBE can be found on Cisco.com. www.cisco.com/go/cube > Configure > Configuration Examples and TechNotes > Unified Border Element (CUBE) Session Initiation Protocol (SIP) Normalization with SIP Profiles Configuration Example. An example of transcoding configuration on the CUBE can be found on Cisco.com. www.cisco.com/go/cube > Configure > Configuration Examples and TechNotes > Unified Border Element Transcoding Configuration Example. An example of TLS configuration on the CUBE can be