/mcpDescription Setting From the drop-down list, choose the outgoing transport mode. When Device Security Mode is Non Secure, choose TCP or UDP. When Device Security Mode is Authenticated or Encrypted, TLS specifies the transport type. Note TLS ensures signaling integrity, device authentication, and signaling encryption for SIP trunks. Note You must use UDP as the outgoing transport type only when connecting SIP trunks between Unified Communications Manager systems and other application do not support TCP. Else, use TCP as the default option. Outgoing Transport Type Check this check box to enable digest authentication. If you check this check box, Unified Communications Manager challenges all SIP requests from the trunk. Digest authentication does not provide device authentication, integrity or confidentiality. Choose a security mode of Authenticated or Encrypted to use these features. Tip Use digest authentication to authenticate SIP trunk users on trunks that are using TCP or UDP transport. Enable Digest Authentication Enter the number of minutes (in seconds) that the nonce value is valid. The default value equals 600 (10 minutes). When the time expires, Unified Communications Manager generates a new value. Note A nonce value, a random number that supports digest authentication, gets used to calculate the MD5 hash of the digest authentication password. Nonce Validity Time Security Guide for Cisco Unified Communications Manager, Release 15 and SUs 188 Basic System Security SIP Trunk Security Profile Settings