Help T1 and Infrastructure, Out of my Depth


Junior Member
Jun 22, 2002

I am out of my depth and I know someone here has experience and can lead me to the answers I need. I have been tasked with meeting with the architech of a 17,000 sq. ft 2 story building. The owner are going to have a T1 put in and lease communications to their renters. I understand that with a T1 you can have up to 24 seperate phone line + internet connectivity. I would like the forum to comment or point me to information concerning T1's in genera and what special need or problem may be encoutered with this setup. Most importantly I would like information to relay to the architect on the special need of the communication/telephone/IT closet.

If this post require a response that is to long for the forum please email me at

Thank you for letting me pick your collective brains.



Senior member
Jul 18, 2002
One concern that I would have right of the bat is bandwidth. A T1 connection is 1.55 mps. How many renters do they plan to have in that building? If the building were rented to 6 different businesses with 5-20 users each, and all of those businesses shared the T1 line... it would be pretty darn slow.

Have the owners put forth and numbers on how many people with be in the building on the internet, or made any statements about bandwidth?

Also, the owners needs to make sure that they obtain a large pool of IP addresses that can be given to the renters as needed. Some of the renters are going to want servers set up (e-mail, web, etc.) and they are going to need some IP addresses to make that happen.

Good Luck!


Senior member
Mar 5, 2002
A T1 can be used for voice or data. If it is being used for voice it can carry 24 digitized channels (lines), and if it is being used for data it can handle a throughput of 1.544mbps, essentially 24 channels at 64kbps per channel.

Telcos offer variations these days. You can get a PRI which is a voice T1 coupled with all of the goodies (caller id, call waiting, etc), or have them split the channels and use 12 channels for voice, 12 for data, etc.

Say for instance you never anticipate having 6 inbound/outbound calls at the same time, then it would not make sense to dedicate anything greater than 6 channels for voice.


Platinum Member
Mar 27, 2001
Since you're talking about building the structure, rather than actually supplying services to the tenants, why don't you figure out what physical space/layout they need.

I am Not An Expert!

It seems to me that you'd need a smallish "wiring closet" at or very close to the external wiring point for the TelCo.
It'll need space enough for a PBX, a router or two, T1 termination, racks to connect/mount the equipment, potentially different secured areas for each tenants, etc... (15'+ x 15'+????)
It'll need AC power, preferably from two different sources/circuits, and you may need to consider UPS and/or generator.
It'll need HVAC, and enough power to run it. This equipment gives off heat, and doesn't work well when it's hot.

You'll want at least one (maybe two) "wiring closets" on each floor, to patch the (local) workstations/servers/telephones in to the TelCo. Each "wiring closet" will need some sort of conduit/access to run the network backbones from floor to floor and to the TelCo wiring closet for the building. Think: one Switch in each closet for each tenant, with all the clients connected to the switch. Each switch connected to the other wiring closets, which provides connectivity to the TelCo closet. Don't forget, the phone wiring as well, which would set up in a somewhat similar manner.


Senior member
Apr 19, 2001
Good Answers so far.

T-1 is delivered on 2 pair of UTP wires.
It is terminated in a small box called a smart jack. The smart jack is line powered, and is the last piece that the Telco owns.
Usually, the smart jack is near the entrance of the wire that the T-1 is carried on. After the smart jack, you can run the T-1 anywhere in the building on UTP. That usually ends in an "extended demarc", a RJ48 jack. (Looks like an RJ-45, but loops the t-1 if nothing is plugged into it.

Small, no power requirements, place it anywhere it can be locked.
The Circuits are not a big issue. The equipment ...
Woodie?s points are probably what you are asking, but I thought it would help if I furnished a bit of background.
No Sonet equipment is a fish of a different color, but that?s for another thread.




Diamond Member
Feb 26, 2001
Originally posted by: elmo911
Most importantly I would like information to relay to the architect on the special need of the communication/telephone/IT closet.
From what I recall the last time I was involved with a new building project, some of the biggies were (Woodie got some of these):

* PLEASE GOD NO SPRINKLER SYSTEMS OVER THE EQUIPMENT (not always possible, depending on fire code).
* Sufficiently sized grounding bar for your telco, local wiring, etc. folks to tie all their stuff into the common building ground. VERY important (and often overlooked)
* ENOUGH SPACE TO WORK BY GOD in and around any racks, equipment installed anywhere.
* Sufficient amounts of mounted plywood, preferably painted and at a reasonable working height
* Suffficient open/dedicated conduit for both ingress and egress wiring.
* Centrally located closet, but AWAY from elevators, firewalls, if possible.
* Closet for each floor, with closets located directly above one another.


Moderator<br>Networking<br>Elite member
Mar 19, 2001
If there's gonna be equipment in the closet, put lots of power (from many different circuits), and don't forget to have sufficient air circulation and air conditioning. Filtered air would be good, if you can swing it (dust-free would be a wunnerful thing, but it usually doesn't happen).

There are cabinets available (Liebert, for example) that have a built in air conditioner / filter / dehumidifier, so you don't have to do the entire closet. Also, if the closet is small (and you buy a decent quality cabinet), you can roll the cabinet out of the closet to load it and/or work on it ... generally not recommended, but I've seen it done with some success.

BTW: Real, official, T1 "premises cable" is double shielded: each pair is shielded, then there's another shield that surrounds both pair. Most CSU manufacturer's accept Cat5, plan on Cat 5, design around Cat5 .... but Prem cable is is the spec, I believe.

Battery backup for the closet lighting is also a nice thing, if you can get it.

An extra phone or two is also a good thing (especially when you're calling tech support and they want you to be looking at the stuff while working the case).

A lockable / sealable storage cabinet is also handy for commonly used tools / supplys / cables, etc.

AND, if you want a *REALLY* nice closet, don't forget an outlet for the Beer 'Fridge, and the ventilation hood for the Weber grill.....couple Lazy Boys, antenna feeds, boom box .. the list is almost endless.




Diamond Member
Feb 26, 2001
A ceiling is very important. Don't EVER let anyone take the ceiling out of your new data room!

Don't laugh...the idiot boss I had at my last job had the ceiling removed from the "showcase" server room at our new corporate HQ when it was being built a few years ago.

His response when I asked him about it?
"We don't have a ceiling in our server room over here (plant location)!"

His response when I showed him the ceiling?
"Well...what do you know..."