how many of those can you dial direct from outside xxx 8900, xxx-3000 ? those are your did's.. in the switch i maintain the complete nxx are my did's any number i add is a did xxx + 0000 thru 9999, are routed to the hospital. you may well have 400 did's for a average size switch.. find a vacant number, prt a simular set and you'll see the key entry for a did, it looks almost the same as a non did. the big difference is the pstn routing
john poole
bellsouth business
columbia,sc