Per the features guide, you would need to make a few changes in LD 15:
Code:
REQ CHG
TYPE NET
CUST 0
...
ISDN YES
-PSTN NO [COLOR=red]Places no limits on PSTN connections[/color]
...
TRNX YES [COLOR=red]Allows for transfer of ringing trunks across private network trunks[/color]
EXTT YES [COLOR=red]Allows connection of external [b]SUPERVISED[/b] trunks[/color]
If you have Trunk Barring (TBAR) configured in your system (LD 56), you can also set FTOP in LD 15 to several options:
(FRES) Default = Flexible Trunk to Trunk Connections Restricted.
FTT (Flexible Trunk to Trunk Transfers) is inactive.
TBFT = Trunk Barring Flexible Trunk to Trunk Connections.
FTT adds new restrictions on connections not barred by TBAR.
FTTB = Flexible Trunk to Trunk connections Trunk Barring.
FTT lifts TBAR restrictions for routes barred by TBAR. FTT cannot add any new restrictions for non-barred routes.
FTLY = Flexible Trunk to Trunk Connections Only.
All Set based trunk to trunk connections for Transfer and Conference are controlled by FTT only.
If you want to allow this, make the changes above in LD 15, then try the options I listed below the code.
Hope thie helps,
Scott M.