SIP Trunk Encryption

SIP Digest Authentication is only an MD5 hash of username, password, SIP URI and other components of the SIP messages.
SIP Digest Authentication does not provide confidentiality of signaling packets
SIP Trunk Encryption can be used for that
- SIP trunk encryption uses TLS for SIP
  - TLS authentication is based on certificates
  - CUCM must trust the issuer of the certificate of the peer:
    - Can be self-signed
    - Can be issued by a CA
  - Subject used in the TLS certificate exchange has to be configured.
  - HMAC is used for authentication.
SIP trunk encryption protects only signaling.
No SRTP support on SIP trunks.

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