[Asterisk-Users] how do I do s extensions with PRI

[firedude at shorelinuxsolutions.com]

I would like to know how to define the s extension when I have an incoming 
PRI line?  Currently I have 5 incoming DID numbers. Four of these DID 
numbers I have going to specific extensions, the fifth number which is the 
main number I wish to go to a background sound where callers can hear 
message, get directory, dial extension, whatever.  I see that the way to 
normally do this would be to define s extensions and then step up the 
priorities for each action I wished to be taken.  However, with the PRI 
line it seems that I can't use the s extension.  I can use exten => _X. 
but this screws up the other four DID numbers which I have going to 
specific extensions.  Is there a way with a PRI that I can define an s 
extension or something like it to save from having to type an entire 10 
digit string multiple places?  

Thanks for any suggestions.
AJ