atcomsystems.ca/forum Forums VOIP Phones & IP PBX Networking DSL bridge cable pairs.

Verizon sold customer dsl service in (2) locations feed by bridge cable pairs via central office.

Customer wants DSL service at both locations which are on the same telephone number.

This would require 2 dsl modems at both locations.

I say it wont fly, because loop limits issue.
Can you have 2 modems with same address ?

I am confused.

It wont work, and i don't think its worth the time even trying it.

Ive never run across this issue, but common sense says no it will not work.

I am having some tense shift problems with this question. However I think it could work. The reason is the way DSL works. Each line must go thorugh a DSLAM card that puts the data on the copper loop. The DSL signal rides on the telephone circuit (copper loop) for part of its length and hops off again at the DSL modem before the end of the copper loop. If the lines are bridged upstream of the DSLAM cards in the central office, it should work.

CO Switch - DSLAM ===== DSL Modem - Phone

In this actual, unretouched photo, a "-" represents a copper loop carrying just voice, while "=" represents the part of a copper loop carrying voice plus data.

If the DSL signal hops off when it reaches the first DSL modem how will the second modem get a signal?

From another DSLAM. Due to the fact that this site doesn't allow more than one blank space, I couldn't really draw it. Here's another try.

CO Switch
|
|-DSLAM========DSL Modem - Phone
|
|-DSLAM========DSL Modem - Phone

If it's bridged at the CO the full signal should get to both locations. Would Verizon allow two different customer modems on the same CO DSL equipment is the question. If they do there is no reason it shouldn't work.

This could be one of those scenarios that work in theory but let's hope the dsl connection isn't important to this business cause the gremlins I have sitting on my shoulder a screaming jikky as loud as they can. They are laughing too, or maybe it's just a snicker. Anyway, get back with us after you take it for a test drive.

I know in my neighborhood when they put DSL in, the first thing they did was take out ALL the bridge taps. I was told that they added too much "something" (capacitance? resistance?) that hosed up the DSL signal and dropped power dramatically on the circuit.

Sam

Yes Sam, only a CO bridge will give a balanced circuit, bridging in the field wouldn't. I just can't see any Telecom allowing multiple modems on a dedicated DSL service.

DSL just "rides" along a copper cable pair. One side of the pair can actually be open and DSL will still work. The copper pair is more of an "antenna" as far as DSL is concerned.

We aren't talking about phone numbers here. Everybody knows that a full copper loop is required for a POTS line to work. We are talking about the possibility of getting one-half of a copper pair to the customer premise. If that can be accomplished, then DSL will work even if the associated voice circuit is dead.

Remember, as Grim illustrated, you have T/R going into the DSLAM in the CO for a particular POTS line. Both the POTS and DSL signals ride the copper pair to the premises. At that point, DSL filters chop out the DSL signal that was inserted by the DSLAM in the CO, so every device except the DSL modem must have one of them..

That same phone number can be sent through multiple ports on the DSLAM in the CO. The DSLAM doesn't care what phone number is riding on the cable pairs. It's just hitching a ride for a clean metallic path to the DSL modem. That same phone number can go out to 10 locations (hypothetically) and still have separate DSL accounts and modems working on them. Remember, DSL is just hitch hiking on an existing copper circuit. It's not picky.

It's really so simple that it looks complicated.

Good point, Ed.

Sam