Asterisk bounty PRI 2B channel transfer

*UPDATE*Bounty closed as of 2007-09-21

*UPDATE*Bounty poster seems to be inactive, mflorell has taken over the bounty as of 2007-08-27

Bounty: PRI 2B transfers

Maintainer: mflorell
Status: Functional in DMS100 in Asterisk 1.4, and beta patch for 5ESS, NI2 2BCT added into libpri trunk by mattf 2007-09-21
Contributors: mflorell (mflorell at-the-domain
Amount: Bounty is inactive
License: will fully disclaim to Digium for use in Asterisk and GPL


This mostly falls under libpri instead of zaptel, but here it is none the less. I need to have asterisk be able to hand off two B channels of a PRI to the upstream switch. This would get * out of the bridge and more importantly, release the use on the channels on the PRI.
Additional information on the 2BCT can be found on John Todd's website. URL is: (seems to be dead link) try*/

Currently Asterisk(libpri/zaptel) 1.4 fully supports this feature on DMS100 switchtypes only, but there is a patch available for 5ESS and Digium is working on a stable version of that for the 1.4 codebase. As for NI2, Digium has no intentions of supporting 2BCT on it any time soon making this bounty very important.

Please contact off-list if you need more info. I will place this back into community so the bounty would take that into account.

This out of the 5ESS manual:
PRI Two B-channel Transfer (TBCT), introduced in the 5E13 software relase, is defined by Bellcore in GR-2865-CORE, and by ANSI as Enhanced Explicit Call Transfer supplemenary service in ANSI T1S1.1/96-346. The Notificaton to Controller (NTC) subscription option to the TBCT feature is available beginning with a software update to the 5E13 software release. A "controller," which is an intelligent peripheral interfaced to the 5ESS switch over an ISDN PRI, can request that two independent calls, each on an ISDN PRI B-channel, be transferred away from the PRI and connected to each other. This frees up the PRI B-channels while the transferred calls are active on the switch. The NTC feature option notifies the controller when the call previously transferred by Two B-channel Transfer has cleared.
These two calls may be on B-channels on different PRIs but, if they are, the two PRIs must be members of the same PRI serving group. At least one of the two calls must be answered; the other call may be answered, or alerting if it is incoming from the controller to the switch.

Created by: oej, Last modification: Wed 15 of Oct, 2008 (05:24 UTC) by hegars
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