Broadband drops when phone rings

[lozcart]

I wonder if anyone has any ideas on what I can try next regarding a problem I've had since the new year.

I found from my router log (2-wire 2700) that in early January 90% of the time my phone rang my broadband connection was dropping. I checked the wiring and replaced the filters on both router and phone a couple of times but to no avail.

I contacted Idnet who ran some line tests which they said showed a fault, they reported this to BT. A couple of days later my broadband dropped a few times while BT where messing with my line and then settled down. BT reported the problem was fixed. For the next couple of days the problem do seem to have been sorted, only to return again.

Both Idnet and myself monitored the connection and found it was still happening when the phone was called, Idnet contacted BT who arranged a home visit. The engineer came didn't test for symptoms just said "it will be your wiring mate, we will change the faceplate" and so a filtered faceplate was fitted. He then tested his work called the phone and guess what my broadband dropped. He then went on to say the 2700 was a business router and might not be compatible with a domestic line but said he would check my connection at the exchange. He called me half an hour later saying my line was fine and it must be the 2700. Idnet have told me BT want to charge me for this visit.

This got me thinking maybe the 2700 had developed a fault, I got my old Belkin from the loft and connected it up, the broadband didn't disconnect when the phone was called, so assumed the 2700 must be faulty. Today a received a brand new sealed 2700 from ebay and set it up, tested it and this also drops the broadband connection when the phone rings. Set up the Belkin again and it's fine.

Could there be some incompatibility problems with the 2700, I do doubt this as I've used one for the last 8 months with no problems or are there other sinister forces at work.

I will contact Idnet again tomorrow but has anyone any ideas on what else I could try.

[Rik]

It's odd. That problem is normally caused by filters, and if you've changed them, unless you've been very unlucky, then they shouldn't be part of the equation anymore. What make did you use?

The fact that it's affecting 2 2700s but not the Belkin is puzzling me. A router is a router is a router, whether you have a domestic or business service, so I feel that's a red herring. What shows on the DSL Diagnostics page of the 2700 against the drop in sync?

I fear you may have to pay the BT charge, unfortunately, as it does appear to be an issue with your equipment, the puzzle is what.

[lozcart]

I've been using the BT filters that come with the 2700. Currently the router is connected directly to the new filtered face plate and the phone via a filter to an extension socket.

If I disconnect the phone from the socket and then ring the line the broadband also drops then. When the line drops it reports ERR LOSS LIMIT.

The drops are killing my connection my noise margin was at 3.0 before the problems it's now up to 15.0 so my sync is suffering.

[Steve]

Have you tried the 2 wire in the test socket with no phone connected?

[lozcart]

I tried it in the test socket before it was upgraded to a filtered faceplate and it still dropped.

I not sure if there is a test socket behind the BT filtered plate, does anyone know?

[Steve]

Could be the same original backplate,either way the lower half should be removable and the test socket should be behind.

[lozcart]

I've spoken to Brian at Idnet and he thinks it may be some incompatibility between the 2wire and the exchange equipment. He is sending me a Netgear test router so we can if it replicates the problem.

[Rik]

Sounds a sensible move.

[MisterW]

On the 'DSL Diagnostics' does the 2700 show OK against Uncancelled Echo and Impulse Noise as in the example below ?

Uncancelled Echo:    -19.3 dB    Ok
VCXO Frequency Offset:    24.1 ppm    Ok
Final Rx Gain:    2.6 dB    Ok
Impulse Noise Comp. Tones:    0    Ok
Excessive Impulse Noise:    0    Ok

[lozcart]

Both say ok and are as follows

Uncancelled Echo -8.6 db
Impulse noise 0

I did notice after one sync earlier in the week the uncancelled echo advised to check filters, this cleared after a reconnection.

[lozcart]

Carried out a few more tests and can confirm the connection still drops when connected to the test socket.

One thing I did notice is if you answer the phone within 3-4 rings the connection usually holds, the longer I leave it ringing the more chance of the connection dropping, not sure if this is relevant.

[MisterW]

I'm not convinced about that uncancelled echo , -8db is not that brilliant I don't think. I'll check mine at home later but I've a feeling that it should be around -20db normally. It might be that you have a marginal fault on the line which is being highlighted when the phone rings. Netgear routers are pretty good at hanging on to a connection at very low SNR (close to zero) values for short periods whereas the 2700 will tend to drop it fairly quickly below about 3db.

[Rik]

Mine is -24.7.

[MisterW]

Mine is -15.8 at home. Assuming the negative number refers to the level of echo BELOW the signal then -8db is not that good and might indicate a problem. As Rik said earlier, normally the uncancelled echo is caused by faulty/missing filters but we seem to have eliminated that so it may just be a line fault, but proving it...

[lozcart]

I can't be 100% sure but I seem to remember my uncancelled error was around -14 or -15 before I experienced the problem, so we might be on to something.

My noise margin when the connection drops indicated on the DSL page is around 15 to 15.4 so it wouldn't appear to be the noise margin causing the drop.

Are the uncancelled error and the noise margin related?

[Rik]

Only indirectly.

[lozcart]

Isn't this just typical  

Received the Netgear router from Idnet this morning (great service)  

Was going to set it up but thought I would ring the line to see what was happening with the 2700, I have called it at least seven times and the 2700 has held the connection every time. Yesterday when I tested it it dropped every time. This happened a few weeks back when the line seemed to settle for a few days only for the problem to reoccur. My uncancelled echo is still -9.5db.

Not sure now what to do except to keep the 2700 connected and monitor it, if the problem comes back then try the Netgear.

I'm confused  

[Rik]

Difficult call. I think I'd be inclined to test with the Netgear for a couple of days, then switch back and see if the problem returns. If it does, go back to the Netgear again.

[lozcart]

Looking at my stats for my current connection which has now held for 24hrs there is one area which is vastly different from my previous connections, this is my upstream stats.

It currently shows connection at 770 with noise margin 11.5, all my previous upstream connections have been in the range of 944 with noise margin of 5.0.

Would this be significant in the line holding connection when I dial it.

[Rik]

It shouldn't be, but it could indicate an improvement in line condition.

[lozcart]

I must have called my line over 30 times over the weekend with the 2wire attached and it never dropped once. I came home at lunchtime today and tested again, first time I called the line dropped the connection which had been solid for three days.

Unpacked the Netgear test router and set it up. Called the line and the connection dropped after 5-6 rings. Waited for reconnection and tested again, line dropped immediately the phone was called, same again the next time.

Contacted Idnet who are bouncing the problem back it BT again.

[Rik]

This is weird.

[lozcart]

It certainly is, its the inconsistent nature of the problem which baffles me.

[klipp]

I had this exact same problem and managed to fix it by double filtering my telephone.

[Rik]

Has to be worth a try, thanks klipp.