1088 Tandem Routing

Tandem Routing provides for access by ESPs to the exchange network with trunk
and/or line interfaces through tandem switches.  This allows ESPs to 
interconnect with the network at a single point and be accessed by customers in
a selected group of end offices, all of which subtend that tandem.  In some 
jurisdictions, at the option of the ESP, calls from a particular end office may
be blocked or forwarded to the ESP, allowing the ESP to create a custom services
area from the LATA sector served by the tandem.

Generic Name of ONA Service 	Product Name			BSE or CNS
===========================================================================
Tandem Routing			AM - Tandem Routing		BSA **
             			BA - Tandem Routing		BSE
             			BS - Custom Service Areas	BSE
             			NX - Tandem Routing		BSE * 
             			PB - Tandem Routing		BSA **
             			USW - Tandem Routing (FG D)	BSA **

* For NYNEX, this service is also available with the Circuit Switched Trunk
  service BSA.
** For Ameritech, Pacific Bell and U S WEST, this is met by an alternative of 
   the Circuit Switched Trunk BSA.

FEATURE OPERATION:
Tandem translations supply data for routing calls over tandem trunks.  Tandem
trunks that are incoming from a tandem office or central office cannot terminate
at a line or tone circuit in a local office, with the exception of a connection
to reorder tone when all outgoing trunks are busy or a network blockage occurs.
Instead, these trunks are switched to tandem completing trunks that are
outgoing to a local office. 

TECHNOLOGICAL AND FEATURE INTERACTION CONSIDERATIONS:
1. This feature is available in the following central office switches:

Switch Type			1A ESS	5ESS	DMS-100
Earliest Generic Release	1AE8A	5E2(2)	BCS19

2. All three switch types require specific generic software to configure the
   switch for tandem operation.  An example of this is the Northern Telecom 
   NTX386AA feature package, used in the DMS 100/200 to configure this switch 
   for Access Tandem capabilities.  This feature package enables access tandem
   translations and screening, trunking, treatments, and billing as well as 
   various software support features.  Because all offices do not contain the 
   necessary feature packages for tandem trunking, the local exchange company
   must be contacted for specific geographic locations of the switches with
   this capability. 

3. In some regional companies, this service may be limited to Feature Groups B
   and D, or Feature Group D only.

4. References: TR-TSY-000540, Tandem Supplement to LATA Switching Systems 
   Generic Requirements (LSSGR), Issue 2, July 1987, Section 5.2.

This service, if offered as a BSE, is associated with the Circuit 
Switched Trunk basic serving arrangement.
