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[NewtronStar]

Hopefully this is in the right place, recently when I make a call on the the land line the SNRm will drop suddenly and when I hang up it recovers with CRC & ES as symptoms.

Will this be a Phone or Broadband issue that needs looking into by Openreach if this keeps happening ?

 

[NewtronStar]

Have used the ringback facility 17070 and this does not change or effect the SNRm it only happens during a phone call out as seen in my last 17070 quiet line test graph for a few minutes.

[burakkucat]

What you have described appears to be the classic manifestation of the start of a HR or semi-conductive joint. Do you hear any noises when performing the quiet line test?

In terms of making a fault report, as it is a problem with the physical infrastructure -- the metallic pathway, it should be reported as a telephony fault. But before attempting to make a report, have you tested with a different telephone? Would a neighbour be willing to lend you their telephone, just for a quick 5 or 10 minutes?

[NewtronStar]

Cheers BC the quiet line test is very quiet indeed when using the BT4600 Dect handset which is only five months old don't have a corded phone at the moment.

Just made another call on the landline this morning and the VDSL link went down with ES and changes to line stats like sync and SNR lost the 3dB profile and back to 6dB

Will call EE tomorrow and grab corded phone to-day.

[toulouse]

I went through the associated rigmarole a couple of months ago, having reported the same / similar problems at the beginning of the year through my ISP. In all I have had 3 BT Openreach visits, and after each the problem disappeared for a while and then kept coming back. However, since the last visit things have been a lot better, and I am now on (what I think is a) very stable 34999 DS/5712 US, with a 3.6 DS/6.0 US SNR. I did notice that after all the shenanigans that my interleave level has risen from a fairly consistent ~750 to the present level of 1485. There is also no noise at all during either incoming or outgoing telephone calls.

Not sure if any of this is of any help in resolving your issue, but you may need multiple Openreach visits to finally get it sorted.

Good luck

[NewtronStar]

Thanks toulouse any info is most welcome as this is first time I've had telephone issues that either drops the VDSL SNRm or signal when in use, Just for interest have got hold of a corded phone and used option 2 QLT the line seems very quiet and SNRm drops again but this time no resync.

[burakkucat]

You have now confirmed that the problem originates with the actual circuit (line) and not with the telephone currently being used.

[NewtronStar]

I'll be on the the phone to EE tomorrow and go through there check list just thought it might fix itself over the last 3 weeks.

[NewtronStar]

Get ready for this the Modem I was using was causing the SNRm to drop when using the phone ZyXEL 8924, I really don't understand how this could happen as the modem is located nowhere near the master socket 5C where the phone is plugged in it is using the data extension terminals into another room 8 meters away.

Billion 8800NL MK1 back in the same place as 8924 and Issue fixed

[burakkucat]

Thank you for the update.

I'm glad to know that you have resolved the problem by swapping out the modem/router. However I am not sure what physical defect would give rise to that problem.

Puzzling. 

[kitz]

I too am puzzled how the modem could cause High Open type symptoms.... but glad you sorted it

[NewtronStar]

Nether do I BC the modem has Firmware version Version 1.00 AAKL 20 loaded into it yes a bit old but should not cause symptoms like this unless the power supply has become weak and modem struggles to maintain a correct current/amp, yes this modem has dual VOIP and is trying to kick in during a call but it would need to be connected to a phone which has two sockets at the back of modem.

[burakkucat]

I've given the problem some more thought . . .

All modems (modem/routers) have a high-pass filter before the analogue front end (AFE). At the very minimum that high-pass filter will be two capacitors, one in each leg of the pair. The normal condition, with the modem (modem/router) powered on and the telephone not in use, will be a high impedance condition. When the telephone is in use, it loops the pair and a low impedance condition prevails. That's perfectly acceptable and is part of the design specification.

Now suppose one of those two capacitors that form the high-pass filter is somewhat degraded, is out of specification, is a bit manky. The impedance will not be anywhere near as high as expected by the design. When the telephone is used, the modem's (modem/router's) interface will be shunted far more than that of the design specification and it reacts adversely . . . That adverse reaction could, possibly, be as was described in the opening post.

As to whether that is a sensible proposal? 

[NewtronStar]

burakkucat if you want I could send this ZyXEL 8924 to you free everything works just the above issue

[burakkucat]

Thank you for that generous offer but I shall decline. 

Perhaps there is a member, with good eyesight and an oscilloscope, who could fault-find and effect a repair?