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Overview:
Feature F-1638 Release Link Trunk utilizes the Two-Bearer Channel Transfer technique for ISDN NI2 to off load two b-channels which are bridged or looped on the IMG. If there are two calls active on the IMG and they are bridged or looped together the resources on the IMG are being used inefficiently. With this feature the IMG has the ability to send specific facility messages back to the Stored Program Control Switch (SPCS) on the PBX or TDM switch and tell the PBX/TDM switch to connect these two calls together so they are no longer active on the IMG. This would effectively open up two b-channels on the IMG that were initially being utilized. TCBT is initiated from a SIP Refer message and is supported from ISDN to SIP only. Below is information on how TCBT is utilized and configured on the IMG.
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