In this section:
The SBC Core supports Call Back When Free (CBWF) feature, also known as Ring Back When Free (RBWF), for UK-ISUP, IUP, SIP-I and SIP interworkings. When the SBC is configured for CBWF support (callBackWhenFreeSupport
flag)
, a call is automatically established to a destination number that was previously busy without the need for the calling party to redial the number.
set profiles signaling signalingProfile <profile name> egress egressFlags callBackWhenFreeSupport <disable | enable>
The SBC, Ribbon GSX and ASX support CBWF for the following protocol interworkings (see call flow diagram):
CBWF is implemented on the SBC using four separate but related signaling sequences described in the table below.
The SBC Core also supports following configurations:
CLI command syntax:
set profiles signaling isupSignalingProfile <profile name> sendAPPinAPMforCBWF <supported | unsupported> set profiles signaling isupSignalingProfile <profile_name> sendPRIonRELforCBWF <supported | unsupported>
If the SBC is configured for CBWF and if a CONFUSION message contains Cause 99 or Cause 110 indicating an error in the APP parameter is received on the SIP-I leg, the SBC releases the call.
This functionality takes precedence over the ISUP Signaling Profile flag transitCfn
used to transit the CONFUSION message towards the other leg.