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Overview
The
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
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.| Code Block |
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set profiles signaling signalingProfile <profile name> egress egressFlags callBackWhenFreeSupport <disable | enable>
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The
, Sonus GSX and ASX support CBWF for the following protocol interworkings (see call flow diagram):- SIP-I (UK-ISUP) to BT-IUP interworking over GW with Sonus GSX.
- SIP to SIP-I (UK-ISUP) interworking
- SIP-I (UK-ISUP) to SIP-I(UK-ISUP) interworking
- SIP to BT-IUP (supported on GSX only)
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| 0 | Figure |
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| 1 | SIP Protocol Interworking Using CBWF |
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CBWF is implemented on
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the
using four separate but related signaling sequences described in the table below.| Caption |
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| 0 | Figure |
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| 1 | CBWF Signaling Sequences |
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| Signaling Sequences | Usage |
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| Call Back When Free - Request | Calling party requests the registration of CBWF at the Originating and Terminating PBXs. | Call Back When Free - Free Notification | Notifies the originating network about the status of the called party. | | Call Back When Free - Call Set-Up | Establishes call between the requesting and desired extensions. This follows the receipt of a Free Notification when the extension is/becomes free. | Call Back When Free - Cancel Request | The calling party cancels the call, or when a CBWF Request is canceled as the result of a timeout. |
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Additional CBWF Configurations
The
also supports following configurations:- Sending CBWF-related APP (ACI=126) in a new APM (Application Transport Message)
- Sending PRI/APM message during tear down of CBWF call for SIP-to-SIP-I interworking scenario.
CLI command syntax:
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set profiles signaling isupSignalingProfile <profile name> sendAPPinAPMforCBWF <supported | unsupported>
set profiles signaling isupSignalingProfile <profile_name> sendPRIonRELforCBWF <supported | unsupported> |
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the 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, |
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the releases the call.This functionality takes precedence over the ISUP Signaling Profile flag transitCfn used to transit the CONFUSION message towards the other leg. |