sundance-communications.com/forum Forums General General Telephone & Systems Information LEC PBX Trunk lines - technical information???

I'm trying to figure out how PBX Trunk lines works. I have an old Rolm system. It is connected to the PSTN with PBX trunk lines from SBC. Since I am not too familar with Trunk lines, how do they actually connect to the switch.

Records from SBC show that I have 57 Trunk lines coming into my premise. But on my switch, it shows I have 100 trunk lines connected.

Question I have is, when SBC lands a trunk line, is it broken up into 2 trunk ports on the switch? Or is it a 1:1 ratio? I'm sure it's the same for any switch, but I can't figure out if I am missing inventory.

Thanks much!
Tommer

Tommer:

Standard trunks, which is what you sound like you have, enter the system on a 1:1 basis. This applies for loop-start, ground-start or DID (direct inward dial) trunks. Most Rolm systems use ground-start or DID, loop-start is generally not preferred on larger systems.

I think that you do have 57 trunks coming in, but the system is equipped for 100. The remaining 43 are just vacant ports available for expansion. It's also possible that one or more of them can be used for access to external devices, such as external paging.

I'd hate to see your phone bill.

If you have 57 trunks coming in on copper lines you should be talking to a CLEC vendor.

You are at a 3 T-1 configuration and my carrier of preference (at the moment) would probably finance the cost of a new system over three or four years and still save you money every month.

57 copper lines? OY VEY!

Yeah, the phone bill is great.. ugg.... after my research, i saw the how the 1:1 works with the trunk member ids. I am running a traffic report next week from commview to see what is actually turned on. I have a feeling that there a number of trunks no longer around.
So yeah, it's a mess. I'm moving it all to PRIs eventually once I get CallManager up and running.

Fun stuff. Thanks everyone!