For some reason dense analog solutions seem to give everyone a headache.
Well thanks to the xLEC’s getting out of the fractional T1 business (kind of hard to sell a sub 1M Internet connection these days) there are literally thousands of channel banks for sale at outrageous prices.
A channel bank is a very simple device. It takes a channelized T1 (from a gateway or a DAHDI card) and breaks out the constituent 24 analog channels. For our use we use FXS ports but you could use a mixture of FXO/FXS/GS/E&M etc. if you want to bring it TIE trunks from an old PBX or POTS lines.
Attached is a picture of the rack. This is 16 T1’s. Each of the 2U Cisco routers have 8 T1 Multiflex (voice and date) WIC cards in them. They are setup SIP and are simply SIP extensions from Asterisk’s perspective
The 1U router at the bottom has two more T1 interfaces and is the gateway for the PRI’s. It converts the PRI’s to SIP.
The little silver 1I box at the bottom is a 48V DC inverter. The channel banks run on either DC or AC. To me why rectify the power twice so I run it all DC (the thing on the side of the rack is a fuse panel) but it’s really not necessary and unless you are familiar with -48 wiring and practices I would recommend the normal route and a UPS.
So anyway, this stuff is fun, the next time you need to do an installation with a large quantity of analog extensions look into this solution. You will differentiate yourself from the competition and deliver real value in the process.
Here is a PIC