sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Basic Info and help with T1?

Hello everyone,

I apologize, but i am just starting school and learning IT stuff and haven't hit the T1 info yet. However, the company I work for is expanding into a new building and I know more about computers than any of them (imagine that lol)and I have a meeting next week w/ the people installing the new phone and network equipment.

I was wondering if someone had the time to explain to me how exactly a T1 works. I know that the plan is to get a T1 line with roughly 100 DID's, (that's basically the total amount of direct phone numbers right?) and the T1 will be used for both internet and phones so we are looking at VOIP (I think).

So if I understand this correctly, we have to choose the # of lines that will be dedicated to the phone system and the rest will go to the internet and that is out of the 24 possible lines that can be used at one time from a T1 line right? I believe as of this moment we are anticipating up to 10 people on the phone at one time, we are not a very large company.

Also, can faxes be sent through a T1 line and if so when receiving a fax that uses one of the 10 lines we selected to be set to the side for the VOIP?

Thank you soo much for taking the time to answer this. I am just trying to ensure I'm on the right track before the meeting I have to go to next week. Best wishes!

You're really asking quite a bit.

A T-1 is a 4 wire (2 pair) digital line with a bandwidth of 1.544 mbs consisting of 24, 64Kbs channels. You can use all or some of these channels for Voice or Data. You could, for example use 12 channels for voice and 768KBS for Data services.

How many channels you choose for voice and how many for data is between you and your carrier. Remember - there are outgoing as well as incoming calls and all must be addressed.

Faxes can be sent over a T-1 and when you are sending and/or receiving a fax it takes up one of the channels.

I would suggest you pick up a copy of Bill Flanagan's book: A Guide to T-1 Networking. It's old but it's got a lot of good information in it. It will NOT tell you how to install, or repair T-1s but it WILL tell you how they work. You can find it on Amazon:
https://www.amazon.com/Guide-T-1-Ne...mp;s=books&qid=1263596394&sr=8-1

Sam

Until we know what you are getting, we can't give you a lot of information. As was mentioned above, a T1 is 24 channels on a digital circuit... but are you really getting a full T1 or are you getting integrated access or are you getting a PRI?

You also mentioned VoIP, but are your getting a VoIP phone system or are you getting SIP trunks from an ITSP?

You have your work cut out for you. I'm very sure that everyone here will help as much as possible, but your question might be akin to explaining the details of GRE over a VPN and how all that works with TCP/IP to a noob.

I'm not being smug...just letting you know that many often mistake the voice world as a bit more simplistic that it truly is.

A less technical answer may help you get started. To use both voice and data on a T-1 you need an integrated T-1. In your case, 10 channels would be dedicated to voice and the remaining bandwidth will be your data. However, you may prefer a PRI. PRI delivers name & number but a T-1 can deliver number only. PRI uses the last channel for its data so 64K will be unavailable for V/D. A fax line can work over a T-1/PRI but many providers push a dynamic T-1 and faxes are unreliable on them. A dynamic T-1 is VoIP but does not require a VoIP system. SIP trunks do require a system with VoIP cards but does not necessarily have to be a 100% VoIP system.

Here's a great thread to expand your confusion:

https://www.sundance-communications.com/cgi-bin/ultimatebb.cgi?/ubb/get_topic/f/17/t/000193/p/1.html

Good luck. :toast:

Wow you guys are great! Thanks for getting back to me. I know this is all well above my head and appreciate you guys taking the time to give me some feedback.

I know that our phone system is going to be a VOIP system, what all that entails I can't tell you as of yet. I'm still waiting to have the meeting to get more specifics.

Our original plan was to have 10voice lines and the rest of the T1 to be given for the internet, however as of this morning they want to change the T1 to have 13 voice lines and the rest to the internet, it is logical to assume that the internet speed will drop once this decision is made correct?

How do I tell if I am getting a full T1 or an integrated one? I'd like to assume that we are getting a full T1, does getting an integrated one slow down the speed? The building is being constructed as we speak, which is why I'm assuming that the line we are getting will be a full T1.

I wish they wouldn't have ignored my request to be included in the meeting last week. I could have provided you guys with more information.

Just so you know, I am not installing the T1 (I'm sure several of you just cheered lol) I am just the internal network person (minus the education, hense why I'm going to school). I just needed an over view of T1's so I could be a bit more prepared when I do finally get to meet with the people installing the equipment.

Thanks again for all of your help!!

If you're dealing with a traditional TDM setup, then you will have to delete channels of bandwidth to add channels of voice.

If you are dealing with a VoIP T1, then it could be a full T1 of Internet; when a phone call is made, the bandwidth is dynamically assigned to the phone call. The Internet would slow down some, and then pick back up once the phone call is complete.

Your service provider would have to tell you if it is a TDM or VoIP T1.

If you will be using 13 channels for voice then that leaves you 11 channels for data.

11 x 64kbs = 704kbs

That's the maximum you'll have, unless they do some dynamic allocation (turning on voice channels as required and throttling the data side up or down).

Sam