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Pete thanks for the info

We have a DMS-500 in the office so I've never seen something like that done.

in the office?

DMS-500 supports it too

That's odd. I've never actually run across anyone using, or even mentioning that feature in any of the installs I've done in that switch. :confused:

(I'm a CO tech, not a CPE vendor)

From my copy (pdf) of 'Translations 10 of 25'
DMS-100 Family
North American DMS-100
Translations Guide Volume 10 of 25
Data, ISDN, and Internet Services Part 3 of 3

7-20 Datafilling NI0 NI-2 PRI 7-20 7-20
PRI two B-channel transfer

Ordering codes
Functional group ordering code: NI000015
Functionality ordering code: NI000018
Release applicability
NA009 and up for Notification to controller and TBCT across D-channels.
NA008 and up for base TBCT feature.
Prerequisites
PRI two B-channel transfer has no prerequisites.
Description
PRI two B-channel transfer (TBCT) capability on National ISDN 2 (NI-2)
primary rate interface (PRI) trunks gives customer premises equipment
(CPE) more efficient use of trunk connections for calling traffic. With a
private branch exchange (PBX), or a network of PBXs, multiple call forward
and transfers are typical. When a forwarded or transferred call is set up
using two B-channels in a PRI trunk, the original channels can be released
and made available for future calls. The controller can be an intelligent
peripheral (IP), a private branch exchange (PBX), or other customer premise
equipment (CPE).
The CPE requests TBCT by sending a Facility message with a TBCT invoke
component in it to the Service Switching Point (SSP). If the SSP determines
that all validation criteria pass (for example, bearer capabilities and feature
interactions), then the SSP performs TBCT. The SSP responds with a
facility message that acknowledges the TBCT request.
All billing, including AMA billing, proceeds as if the TBCT transfer never
occurred.
Note: For per trunk signaling (PTS) trunks, the system denies TBCT during
the alerting phase. PTS trunks outpulse digits to the far end. TBCT disrupts
digit outpulsing, and the call cannot be completed.
Operation
PRI TBCT provides the capability to connect two indenpendent calls (the
calls may be on the same or different NI-2 interfaces between the controller
and the DMS) at the request of a controller. The system sends this request to
the SSP in the form of a Q.931 FACILITY message containing an invoke
component coded with a TBCT operation identifer.

Translations table flow
The PRI two B-channel transfer tables are described in the following list:
• Table SVPRIGRP defines Serving PRI Groups. All PRIs that belong to
the same Serving PRI Group are viewed as terminating at the same
destination. When requesting TBCT across D-channels, (that is, across
PRI interfaces), the two PRIs must be in the same Service PRI Group for
the request to be accepted. Through table SVPRIGRP, the operating
company can create up to 1022 serving PRI groups. A serving PRI group
is identified through the key PGRPID in table SVPRIGRP. This key is
referenced in table LTDEF to identify logical terminal identifiers (LTID)
that belong to a serving PRI group.
• Table LTDEF defines the service profile of an ISDN logical terminal
(LTID). The key to this table is an LTID. An LTID consists of a logical
terminal group (LTGRP) from table LTGRP and a logical terminal
number (LTNUM) in a range of 1 to 1022. This table must be datafilled
to provision primary rate interface (PRI) and basic rate interface (BRI)
services. The type of service requested is distinguished by the
LTCLASS field, for example, BRAFS, PRA, and BRAMFT. Based on
the type of service, logical terminal specific options can be datafilled
against a particular LTID. The PGRPID field in table LTDEF associates
the LTID with a Serving PRI Group.
• Table LTDATA (Logical Terminal Data) stores service-related data
associated with the logical terminal identifier (LTID [field LTDKEY]),
which is the key to this table. Field LTDKEY consists of three parts: the
logical terminal group (subfield LTGRP), logical terminal number
(subfield LTNUM), and logical terminal data type (subfield
DATATYPE). The TBCT option must be datafilled in table LTDATA for
the TBCT request to be accepted. In the case of TBCT across
D-channels, TBCT must be datafilled on both PRIs involved in the
transfer.
• Table BCCOMPAT (Bearer Capability Compatibility) defines the bearer
capability (BC) pairs that are compatible with one another. For example,
a terminal with a 300-baud modem BC can communicate with a terminal
with a 300- to 1200-baud modem BC. TBCT calls are accepted only if
the two calls involved in the transfer have compatible bearer capabilities.

hope that helps. it seems like if you didn't build out the switch you wouldn't need to know about TBCT because it is automatically included (?)

Where have you been hiding, Pete? We sure could have used you several times this year. Don't be a stranger.

Nope.

Switch provisioning is done by other departments. I'm the person who does the final turn-up with CPE vendors.

My co-worker said that we had a customer about 2 years ago who used that feature.

Ed, I've been hiding in the phone room

Have client in NJ. opening office next week US lec vender. will have split t1,120 did, trunk transfer listed above. 11 channels pri, B-channel. Same client uses identical setup in Del. office. Headaches during setup but makes client happy.------------John