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Different line same ISP?

chaoticmess
Grafter
Posts: 53
Registered: 12-12-2007

Different line same ISP?

Hi,
I’m hoping someone can help me understand how ADSL works in regards to connecting to an ISP on a telephone line that isn’t the designated line for that ISP. By that I mean if you have telephone line A and telephone line B both with different telephone numbers. While also having on line A ISP 1 and on line B ISP 2 providing internet access, can you use the username and password for ISP 1 on Line B, connecting with ISP 1’s IP?
27 REPLIES
Community Veteran
Posts: 26,657
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Registered: 10-04-2007

Re: Different line same ISP?

No
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
PeeGee
Aspiring Pro
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Re: Different line same ISP?

There is probably an "exception" case, if the two ISPs are, for example, "Plusnet by another name", ie Plusnet, madasafish, ... it should work (but not having tried it, I do not know Roll eyes ) Otherwise as per @jelv
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
Community Veteran
Posts: 26,657
Thanks: 884
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Registered: 10-04-2007

Re: Different line same ISP?

Not quite accurate. If the ADSL login domain is the same (e.g. for most Plusnet users it is @plusdsl.net) it may work. However even then some ISPs may restrict the full user login to a particular line (Plusnet don't).
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
chaoticmess
Grafter
Posts: 53
Registered: 12-12-2007

Re: Different line same ISP?

Is Zen internet Plusnet by another name then?
My brother has his own telephone line and broadband coming into the house and so do I. We are on different ISP’s. Since Dec last year I felt things haven’t been right for either of our connections. Mine has fluctuations in the SNR Margin giving occasional disconnects as well as ‘blips’ of non-responsiveness while maintaining the connection. My brother’s connection has had its attainable sync rate decline from 180000kbps to 160000kbps.
I recently attempted to use my router on his connection to see if it would help or highlight the cause of the problem more and when I did I found that the router sync’d and connected using my plusnet username and password before I thought to change it, it even gave me my plusnet static IP and let me download and surf from it. This made me wonder if this was normal behavior and perhaps a possible fault on his/mine/both our lines? The thought going round in my head is that when the BT engineer came round to fix the original fault on my plusnet line in Dec he sort of crossed over some wires or something. The guy was only meant to deal with my plusnet telephone line but managed to pull out all the wires coming out of the ground to the box outside the house. This meant he needed to reconnect them all up again, not just my plusnet line. He seemed to do some basic tests on the other lines confirming ‘this line is defined as ######’ which were correct. However since then our connections have been having problems.
So if my login details for plusnet shouldn’t work could it be the engineer crossed a cable over when putting it all back which somehow is letting this happen? It would certainly explain a lot if this is the case.
I have found that if I disconnect my modem from the master socket his sync speed goes up by at least 1mbps. If I then connect on my line it drops down again. If I disconnect his connection my SNR Margin stays solid at 3.4 and my sync speed goes up to 19000kbps+ instead of 18000kbps.
Is this indicative of a fault or is it normal noise generation from having more than 1 broadband connection coming into the house?
Bright
Grafter
Posts: 363
Registered: 02-02-2013

Re: Different line same ISP?

Quote from: chaoticmess
Is Zen internet Plusnet by another name then?

No.
Quote from: chaoticmess
I have found that if I disconnect my modem from the master socket his sync speed goes up by at least 1mbps. If I then connect on my line it drops down again. If I disconnect his connection my SNR Margin stays solid at 3.4 and my sync speed goes up to 19000kbps+ instead of 18000kbps.

That's due to crosstalk between the two lines. Your ADSL signal is inducing "noise" in his line and vice versa.
EDIT:
Quote from: chaoticmess
I recently attempted to use my router on his connection to see if it would help or highlight the cause of the problem more and when I did I found that the router sync’d and connected using my plusnet username and password before I thought to change it, it even gave me my plusnet static IP and let me download and surf from it.

Both Plusnet and Zen use BTW backhaul to connect your broadband from your exchange to their respective gateways. I'm guessing that both lines terminate on the same DSLAM in the exchange. The port on the DSLAM is probably not tied to specific ISP (since each customer on the other end of the line normally only has one ISP). So you set up a PPP connection from your router to a specific domain (ie xxx@plusdsl.net or xxx@zen) and the BTW network establishes a VLAN to the appropriate gateway. It's like dialling a phone number - it works just as well from his line as from yours.
chaoticmess
Grafter
Posts: 53
Registered: 12-12-2007

Re: Different line same ISP?

Quote from: Bright
Both Plusnet and Zen use BTW backhaul to connect your broadband from your exchange to their respective gateways. I'm guessing that both lines terminate on the same DSLAM in the exchange. The port on the DSLAM is probably not tied to specific ISP (since each customer on the other end of the line normally only has one ISP). So you set up a PPP connection from your router to a specific domain (ie xxx@plusdsl.net or xxx@zen) and the BTW network establishes a VLAN to the appropriate gateway. It's like dialling a phone number - it works just as well from his line as from yours.

Thanks that was nice and clear. Its good to know that is normal.
Quote from: Bright
That's due to crosstalk between the two lines. Your ADSL signal is inducing "noise" in his line and vice versa.

Is crosstalk a fault i can report and get fixed or is this normal too? What would cause crosstalk? Could it be something the BT engineer did when putting the wires all back together again?
Community Veteran
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Registered: 10-04-2007

Re: Different line same ISP?

Has your brother ever been a Plusnet user?
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
chaoticmess
Grafter
Posts: 53
Registered: 12-12-2007

Re: Different line same ISP?

Nope, Was with Nildram then Talktalk now Zen. We purposely don't use the same ISP so if one of us has issues we can use the others till its sorted.
Superuser
Superuser
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Registered: 06-04-2007

Re: Different line same ISP?

I was under the impression that ISPs had to issue orders to BTw for realms to be added on a specific broadband connection to enable it to be routed to the ISP's gateway. On that basis I wouldn't have expected a Zen connection to accept a Plusnet realm (and vice-versa).
However I presume it's possible that a previous routing used on the circuit is still in place in which case multi-ISP connection could be possible.
David
Bright
Grafter
Posts: 363
Registered: 02-02-2013

Re: Different line same ISP?

I wouldn't have expected it either, but it seems to be the case with the OP's two lines, and I can't think of any other explanation. Unless, perhaps, when the engineer was trying to sort out the lines he managed to swap them round and rather than re-wire them again, he got the DSLAM/MSAN (and voice switch) ports re-configured to swap the connections, and both ports were left with both realms configured (although I'd have thought getting those reconfigurations through BT's systems would take longer than swapping a couple of pairs of wires!)
chaoticmess
Grafter
Posts: 53
Registered: 12-12-2007

Re: Different line same ISP?

Between 08:50-09:00 today (Friday) my connection disconnected and reconnected with an SNR Margin of 6.0. The sync speed lowered to 160000kbps and the ping doubled. Restarting and trying a different router has not affected it all which leaves me to believe someone at plusnet saw this thread and tried to help by changing my profile or a setting to give a higher SNR Margin for stability. If this is the case I appreciate you trying to help but please can you undo whatever it was that you did. I don’t consider it a fix or all that helpful especially with the increased ping.
I find it very coincidental for this to happen at the first opportunity a member of staff could change it from making this thread when beforehand it had never done this. Could someone confirm either way if what I think has happened, happened otherwise I have a new issue come out of nowhere now.
While I’m posting again does anyone know the answer to my previous question:
Is crosstalk a fault I can report and get fixed?
After months of trying different things on both my brother and my own connection I’m becoming increasingly convinced the engineer did something to our lines coming into the house which has now given us the problems we have. I have been loath to try and ring/email someone and explain what the problem is because I don’t actually know. It is incredibly frustrating. I know something is not right and as it should be. ADSL+2 got enabled in Feb 2012 and up till November when the telephone line itself developed a crackling on the line everything was fine. Once the engineer came in December to fix it we have been having issues. The cracking is gone so I can’t report that as the fault and I’ve brought new filters, cables and routers trying to make sure it’s not ‘our equipment’. This crosstalk thing seems like a prime candidate for our issues. If things were fine before the engineer came and not afterwards then this leads me to believe he did something to increase the crosstalk or even if crosstalk is not the issue, he did something else to cause our problems. The help I’m looking for right now is how best to explain and get help to fix the problems we now have. For starters which ISP do I contact to explain what’s going on? Do I need to do both? The only way I see things getting resolved is for an engineer to come back out and check everything. I’m just reluctant to start contacting support on either ISP without first having something solid to say is the fault which I feel I may never know until an engineer comes out and checks, catch 22. Which leads me back to the question of can I report crosstalk as a fault? Is it this which is causing the problems?
Bright
Grafter
Posts: 363
Registered: 02-02-2013

Re: Different line same ISP?

Quote from: chaoticmess
...I’m becoming increasingly convinced the engineer did something to our lines coming into the house which has now given us the problems we have.

Forgive me, but I'm not entirely clear what problems you do have. Is it that both lines have a lower sync rate now than they had before the engineer visited to "fix" things in December? If you could briefly summarise the symptoms, someone may be able to suggest a potential cause. It would probably also help if you could post the router (ADSL) stats for each line.
Quote from: chaoticmess
While I’m posting again does anyone know the answer to my previous question: Is crosstalk a fault I can report and get fixed?

Yes and no  Wink
Crosstalk is an inevitable consequence of having ADSL analogue tones on multiple lines that are all in close proximity to each other in the same multicore cable. So a degree of crosstalk is inevitable. Your question is more whether your particular lines are suffering excessive crosstalk as a result of something that may have been done by a BTOR engineer when he last fixed the lines. Probably the only way to get a definitive answer is for an experienced BTOR engineer to check the lines with suitable test gear, inspect the cables, junctions, etc and see if he can improve the performance. And for that to happen, you'll need to demonstrate that you have a fault. Which takes us back to the previous point about symptoms and getting the router stats...
Community Veteran
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Re: Different line same ISP?

Bright,  I feel there is a touch too much theorising going on here.
All this talk of "crosstalk" is misleading. With "normal" phone lines, by which I mean lines without any faults, there is insufficient crosstalk between pairs that would allow you to synchronise with a service on the other pair. It won't matter which DSLAM they end up on or any other common equipment.
The ports on a DSLAM or MSAN are normally very specifically programmed for the domains of a particular ISP, otherwise people all over the place would try logging into their neighbours connections etc etc. Further more you can have next door neighbours on the same ISP, they won't necessarily be on the same DSLAM or MSAN and if on different ones won't necessarily be routed to the same RAS or Node.
If you can connect to your brother's line on Zen and login to your Plusnet connection either there is something incorrectly programmed at the exchange or there is a fault between the two circuits.
I'll post more in a minute, just want to re-read part of the OP's information.
Community Veteran
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Registered: 31-08-2007

Re: Different line same ISP?

@chaoticmess
Just to get some more backgound, who do you pay line rental to for each of the lines?
One thing I don't see mentioned is whether you can log in to the Zen account on the Plusnet connection?
One other thing you can do is run the Quiet Line test on each line - dial 17070 and select Option 2. (don't try any other options). When the system first answers it should give the correct phone number for each line, ensure that it is right.
The lines should be perfectly silent, except perhaps for a barely perceptible hiss. There should be no crackles or any other unusual noises.
Has either line had any other problems with incoming or outgoing calls?
Now, I note that you've said that if you unplug your modem/router, your brother's sync speed goes up.
And visa versa, if he unplugs his modem/router you sync speed goes up.
Both go down when the other modem/router is plugged back in.
This means that each circuit must lose sync when the other modem/router is unplugged and plugged back in again. This far from normal behaviour and is indicative of a fault.
What would be more normal would be to see a slight change in SNRM which should increase slightly when the other modem/router is unplugged. The effect should be similar if the other modem/router was switched off rather than unplugged. This is what is caused by  "crosstalk". Crosstalk is seen by another line as noise.
If either line has an individual fault this can increase the effects. Any intrinsic imbalance on either line can increase such effects because the crosstalk is greater. It would be highly unusual for the crosstalk to be sufficiently large that the one signal appears on the other line. It's more likely that there would be a fault causing both lines to be connected in some way for that to happen.
Whatever the exact cause, line tests should confirm any fault on each line or between them. If a remote test carried out by the line provider showed a fault between two lines it would not identify the exact line, that would have to be done by Openreach.
I believe you are right in the assumption that the engineer that came to repair your previous fault has messed something up, but exactly what he's done is really speculation.
If you can post back and confirm what I understand to be going on as correct as well as the results of the Quiet Line tests and who the Line rental providers are, that will determine the best course of action.