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Tuesday, May 20, 2008

Distance Restrictions In Rural Applications - DSL vs T1

Here's a question often asked by those in rural areas needing dedicated bandwidth for their network applications.

"If someone wanted to have a T-1 line (or fractional T-1) installed in a very rural location, are they subject to the same distance restrictions as a DSL line is?"

The general answer is no. T1's do not have maximum distance "limitation" as does DSL. Network carriers can use multiple T1 repeaters to regenerate (not just amplify) the T1 signal.

However, 2 distance "sensitive" components can increase T1 cost.

First, the T1 access loop. Most local exchange carriers (LECs) (e.g., AT&T/SBC/BellSouth, Qwest and Verizon) charge the ISP for T1 access based on distance between the ISP's router (Internet POP) and the customer's local serving exchange (LEC Central Office.) That is why most ISP's T1 quote tools require the customers local phone number, or at least the 1st 6-digits (NPA-NXX) which identify the local CO exchange, in order to caculate the distance to the ISP's closest IP POP (Internet router).

Second, extrordinary construction costs. If the customer location is a great distance from the closest T1-equipped LEC central office, then the LEC must install additional T1 repeaters and possibly incur other transmission equipment / construction costs to reach the customer. In this case, the LEC has 2 options to deal with construction cost: either absorb cost themselves, or pass it on to the ISP who then pass it on to the end-user customer. I've been implementing T1s for awhile and have seen this situation a few times. Twice the one-time construction costs were $10-$20K and the customer canceled the order. Once, BellSouth had to trench ~200 feet to lay new cable and they absorbed this cost.

Assuming no extrordinary construction cost, there are ISPs that offer flat rate Internet T1s for $750 per month, anywhere in US, with no distance limitations between ISP POP and customer's serving CO. The flat rate cost includes T1 access loop and 1.5 Mbps Internet port. In the majority of cases these aren't always the most reliable providers when you consider long term stability, QoS, and SLA though.

However, for most locatons that are under 25 miles to the ISP POP, we are seeing Internet T1 prices in the general range of $300-$500 per month +/-.

The upside is that it's full speed in both directions, and not subject to the EULA restrictions that DSL lines are. Typically, ISP's don't want you running services behind a DSL line, no such problem with the T1.

Michael is the owner of FreedomFire Communications....including DS3-Bandwidth.com and Business-VoIP-Solution.com. Michael also authors Broadband Nation where you're always welcome to drop in and catch up on the latest BroadBand news, tips, insights, and ramblings for the masses.

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How Does A T1 PRI Really Work

Here's a brief description of the difference between T1 voice vs PRI.....

PRI or Primary Rate Interface is a switched service delivered OVER a T1 connection . If someone were to say I want to order a PRI to location X.?What is being requested is a connection to a trunk side module capable of ISDN protocol to a Telco switch delivered to location X via a DS1 rate (T1) circuit.

Now if someone were to say I want to order a T1 to that SAME location X.??well?That wouldnt be enough info?A T1 from where to where? A T1 for what? By just asking for a T1, nothing is understood or implied about where or what the circuit would be used for. A T1 can be used to truck data at the rate of 1.544 Mbps from one location to another?With channel banks and appropriate DS0 level cards, a T1 can be used to truck up to 24 separate and distinct DS0 signals (analog data, analog voice, or Digital Data Service) from one location to another?A T1 can be used to connect one location to an ISP Internet Edge device to connect a customer to the World Wide Web?In other words, a T1 is a multi use pipe....

With a point to point T1 you can use it for voice and/or data depending on the equipment you have at each end. They are basically just providing the "Pipe" and it is up to you what it is used for.

The thing with T1's and PRI's is it all depends on what equipment is connected to it on each end.

As quoted above, a T1 is just a 24 channel circuit that can be used for multiple things. A PRI is a protocol that uses the 24th channel to control what the other 23 channels are used for.

In a nutshell - a T1 has 24 channels using 56K for data and 8K for signalling. A PRI has 24 channels and uses 23 for data and the 24th for signalling. Also you can break down the channels on a T1 for different type of service. On the PRI all 23 channels have to be the same.

The features.... or lack of.... totally depend on where the circuit is going and what it is connected to on the other end.

Keeping it on simple terms....

PRI is a diffrent protocol to be used with voice services over the T1 line. Where as a t1 line can also be used for voice but without using the PRI protocol and probably using diffrent equipment at the other end to get the dial tone....

Of course....there are a lot more technical details dealing with ISDN lines (PRI's/BRI's) but you've got the basic idea.

The simplest approach to finding the best solution is to request infrastructure design and rate quotes for PRI and/or T1 voice service.... comparing providers available in your area....using the free consultative support of: FreedomFire Communications. Getting expert consultation in this manner will save you time, effort, frustration....and money.

Michael is the owner of FreedomFire Communications....including DS3-Bandwidth.com and Business-VoIP-Solution.com. Michael also authors Broadband Nation where you're always welcome to drop in and catch up on the latest BroadBand news, tips, insights, and ramblings for the masses.

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