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  If initial INVITE is sent with SRTP and IPv4 address and the SBC receives a 488 response code with warning code 301, the trigger action rule 1 is matched and the subsequent INVITE is sent with RTP and IPv4 address in the SDP.
  
  

• If there are multiple action sets for a specific match SIP response code, each action set must be executed serially irrespective of the different error responses received for the subsequent INVITE.
  The execution is stopped when:
  • the SBC receives a 200 OK response or
    
  • all the action sets for a particular rule (matching initial INVITE) are executed.

  Example:
   

  Code Block
  triggerActionRule Rule 1 { Response Code: 488 Warning Code: 301 Action Set1: { Fallback from SRTP to RTP } Action Set2: { Fallback to IPv6 } }

  If initial INVITE is sent with SRTP and IPv4 address, and the SBC receives a 488 response with warning code 301, the subsequent INVITE is sent with RTP and IPv4 address in the SDP.

  If this INVITE does not receive any successful response, the INVITE is re-sent with RTP and IPv6 address.

• If multiple actions are configured for an action set, the new INVITE must be sent based on the combination of all the actions specified in the action set.
  Example:
   

  Code Block
  triggerActionRule Rule1 { Response Code: 488 Warning Code: 301 Action Set1: { Fallback from SRTP to RTP Fallback to IPv4 } }

  If initial INVITE is sent with SRTP and IPV6 address, and the SBC receives a 488 response code with 301 warning code, subsequent INVITE is sent with RTP and IPv4 address in the SDP. The subsequent INVITE is sent as a combination of the actions specified in the action set1.
  
  

• If a specific match (SIP response code and SIP warning code) is not found in the retryProfile, the SBC searches for the response code in the profile and the corresponding action is executed.
  Example:

  Code Block
  triggerActionRule Rule1 { Response Code: 488 Action Set1: { Fallback from SRTP to RTP Fallback to IPv4 } }

  If initial INVITE is sent with SRTP and IPv6 address, the SBC receives a 488 response code with 301 warning code. As specific match for both response code and warning code is not found in the profile, the next match for the "Response code" is searched and the new INVITE is sent with RTP and IPv4 address in the SDP. 
  

Call Flows

Scenario 1

When SRTP is configured and the SBC receives an error response for an SRTP offer, it checks the response code against the retryProfile linked to the IPTG. If the response code is configured on the profile with the action as fallBackSrtpToRtp, the SBC retries the call to the same peer with RTP in the offer. If the Retry profile is not configured or the response code is not present in the profile, the SBC functions with the existing behavior.

Scenario 2

When SRTP is configured and the SBC receives an error response for an SRTP offer, it checks the response code against the retryProfile linked to the IPTG.

If the response code is configured on the retryProfile with the following actions:

• Fall back to IPv4
• Fall back SRTP to RTP

The SBC retries the call to the same peer with RTP and IPv4 address in the SDP. If the profile is not configured or the response code is not present in the profile, the SBC functions with the existing behavior.