2.0 Mb DTI/PRI Administration and Maintenance Guide Book ... - Home

Page 1484 of 1536 Appendix B — Basic and Network Alternate Route Selection (BARS/NARS)
Network Call Transfer
This feature improves the operation of the existing Call Transfer (XFER)
feature between two SL-1s when a call is transferred back to the originating
switch. The regular XFER feature requires two Tie trunks to complete the
call. With Network Call Transfer (NXFER), if the call is transferred back to
the originating switch by means of the same Tie trunk group, the originating
switch completes the transfer within itself and the Tie trunks are dropped.
Both SL-1 switches must be equipped with NSIG and NXFER software for
this feature to operate.
The benefits derived from the NXFER feature include:
— minimal use of access Tie lines
— improved transmission performance since Tie lines are not used for the
completed connection
— operation of NXFER is the same as for the existing XFER feature.
As shown in Figure 144, the NXFER feature allows station A at one ESN
switch (I) to transfer the Tie trunk call from station B (switch II) to a third
party, station C (switch II). In addition to NXFER software, NSIG software
is needed at both ends of Tie trunk. If the transfer is allowed, stations B and
C are connected on switch II and the Tie trunks are dropped (see Figure 146).
In comparison, regular SL-1 Call Transfer (XFER) requires two Tie trunks
and both switches to transfer and connect stations B and C.
553-3011-315 Standard 10.0 May 1999