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On a SIP trunk group basis, you can configure the SBC to accept requests to terminate an active call that is currently set up through the SBC. To clear a call, the request must take the form of an out-of-dialog (OOD) REFER message, and you must configure the SIP trunk group through which the SBC receives the request to locally handle OOD REFER requests (the localOODReferSupport flag must be enabled). In addition, the OOD REFER request must meet the following conditions:

  • The REFER request must contain a Refer-To header in which the method is set to "BYE."
  • A Target-Dialog header must be present that contains valid dialog details that identify the call to terminate.
  • The Request-URI of the OOD REFER must point to the SBC; the host part of the Request-URI must either match a domain name configured on the SBC, or it must match the IP address of the SIP signaling port on which the SBC received the OOD REFER request.

If an OOD REFER does not meet the conditions for clearing a call, the SBC simply relays it if the relayNonInviteRequest flag is enabled. If the relay flag is not enabled, the SBC replies to the REFER request with a 403 "Forbidden" response.

When the SBC determines that an OOD REFER request meets the conditions, it processes the Target-Dialog header to extract dialog information to uniquely identify the target call. The SBC searches for a call setup that matches the extracted dialog information and, if it finds a match, the SBC clears the corresponding call and sends a 200 OK "Success" response to the OOD REFER request.  If the SBC is unable to locate a matching dialog, it sends a  400 "Target-Dialog Not Found" response to the OOD REFER request.

Note

 The SBC cannot terminate a call it is setting up until after it receives a call progress response (receives and processes a 1xx response to the INVITE request).

For information on enabling local handling of OOD REFER requests, refer to SIP TG - Signaling - Local OOD REFER Support - CLI or SIP Trunk Group - Signaling (EMA).