384 Analog extensions on one Atom server - High Density FXS - Channel Bank D4

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


All the cables you see on the floor are from the old PBX. We are in the middle of dressing and cleaning out old wiring.

Nice solution. It is hard to tell from the picture. Are those Adtran TotalAccess 1500s?


I hate to call myself an oldtimer but back in my day…

I started in telephony in the late 90s and this stuff was what we did. It was like therapy to sit on a headin punch punch punch… we would go build out 1000 stations it was an art form.

If I am recalling Markster properly Adrian provided funding when Linux services begat Digium. First time I was there was right after they moved into new building. The place had a great vibe.

Yep, I still carry a 66 and 110 blade. Still needed.

We are not doing any data so those are Adtran TA 750’s

For those that don’t know Adtran is rigt next stoor to Digium in Huntsville.

Technically the adtran campus surrounds digium. That place is insanely large