I want to back up a little to answer your question. Usually 800 service comes in two flavors, one where you have trunks that are connected to your long distance carrier (i.e Megacom 800 service for AT&T). With the other, the 800 number routes the call using a local provider (i.e. 800 Readyline service for AT&T). If you have dedicated trunks, you work withe the long distance provider on which number (DNIS) is passed in the ISDN setup message. This is usually on a per 800 number basis, although there are long distance network features that can route to other DNIS numbers depending on prompting the caller or NPA/NXX routing tables (these are developed by the long distance carrier customer). On the PBX, the DNIS can be an Extension, a VDN or a Hunt Group lead number.
The second 800 service (800 Readyline)routes to a 10 digit number. A call to this 800 number would be routed to CO switch that provides the PBX's local service. It comes in like a DID number (the number that is provided to the long distance company for the 800 number routing must be in the DID range). Depending on how your DID numbers are set up, ARS (for adding or stripping digits) may be involved.
To set up 7 different 800 numbers to seven different hunt groups, you would set up the hunt groups with 7 different hunt group lead numbers. You would then get with your long distance provider. If you have trunks connecting you with the long distance provide, you would give them the 4 or 5 digit hunt group lead number(DNIS).
If you are going to route the call through your local service provider, you would give the long distance provider a 10 digit numbers to route the call. The ten digit numbers would be part of your DID range. The last 4 or 5 digits (Assuming no ARS digit insert or deletion) would be the lead hunt group number.
Hope this helps
Leo V. Brown