Heres the story from start to finish ........

My Gran (who's nearly 90 now) has had a pair of cordless phones to use since she moved in to her house quite a few years ago. The ringing has never worked properly on them but we put that down to being cheap phones.

We decided to upgrade her to something a bit newer a couple of years ago - bought some cordless phones but they only rang once on an incoming call then cut off. They were returned back to the store and we got a refund assuming they were faulty.

A couple of weeks ago, my dad bought her a top of the range set of Panasonic cordless phones. Plugged them in and same problem - only rang once.

He of course rang me and I told him I thought there was probably a fault on the line. He called BT who assured him they'd tested the line and it was fine.

We then assumed faulty internal wiring. I made a trip over this morning to have a look and apart from the spaghetti jungle of wiring, all seemed fine. There was no NTE5 box, the line came in from an overhead cable/pole and into a junction box where it was fed to a boggo cheapo master socket then extensions.

My dad had bought a NTE5 type box from Maplin so I disconnected all internal wiring and hooked it up temporarily. Plugged the cordless in, got the dialtone and rang my Grans number.

One ring then nothing.

Checked cordless phone handbook for ring tones etc - no obvious solution.

Ok - I'm an electronics engineer with my own electronics business so I should be able to sort this. Bunged the meter on - 50v DC when on hook and 79v AC when ringing - thats fine. Then I noticed it was a steady 79v AC when ringing - not a pulsed ring, a constant 79v AC.

Bunged the scope on it - this confirmed it. Constant 79v AC. No cadence ringing.

Sent my dad back home to pick up an old corded phone. Plugged it in and dialled in from my mobile. Once continous ring - no breaks (ring ring, pause, ring ring pause).

Time to call BT .................

Through to what appeared to be an Indian call center. They wanted to run a test on the line and call me back on my mobile.

Give them their dues, 5 minutes later I had a call on my mobile. No fault with the line - it must be our equipment.

I informed him that we'd disconnected everything in the house and testing the two wires that came in provided the same result. I also informed him we didn't have a BT NTE5 type test socket as the house was a rather old one with old wiring.

He then asked me to take the front off the test socket.....

After explaining again that we didn't have one, he told me there was one in the house and I should go and find it. The only NTE5 type socket was one left from an old Telecential install but I wasn't telling him that - it would only confuse him.

He then asked me to describe the socket - I did - 2 screws in the front.

He asked me to remove the screws and plug the phone into the socket behind it. To humour him, I removed the front of the standard master socket and informed him there were no wires behind it. He then told me again that I'd got the wrong socket to which I replied that this was the master/primary socket, the only one connected to the two incoming wires and it had the surge arrestor and ring capacitor in.

Then I told him that I was getting the 50v DC when the line was idle, 79v AC when the line was ringing, scoped the signal and there was no breaks in the ringing and the fault must be at the BT Switch/exchange.

So ......... engineer booked for tomorrow but he kept going on that my Grandma would be charged £150 if the engineer determined that the fault was past the NTE5 box ...... which doesn't exist !

What do you think the chances are of my diagnosis being correct and/or BT attempting to charge my Grandma for a fault thats been at her house since she moved in ?

You may find this gets fixed without a visit to the property, sounds line the exchange line card is ' permenant ringing '..( instead of interupted ringing current)...if the fault receptionist had the faintest clue they would have passed the job to the BT Operate staff (who look after the exchange kit) before passing to Openreach (hence the OR visit and possibility of charges) however the Openreach guy will probably arrange to get the line moved onto another linecard position, by calling BTO and visiting the exchange thus sorting the problem.....given your diagnostics I very much doubt charges being raised, just a pity the fault reports are taken by non engineers.

Indeed - shame I had to get "very technical" to get any kind of result from the person reading from the script card

My dad is going to sit in on the visit tomorrow anyway just in case.

Will update with the results tomorrow

Well an update .........

I wasn't expecting much from BT but so far they have been great. The first engineer rang me to say he was outside the property but nobody was answering the door. As my Grandma is a bit funny about strangers I thought this might be the problem so I rang my Dad who only lives down the next street.

The engineer was fine - said he didn't mind waiting and in the end it turned out he was outside the wrong house lol.

That sorted he spent an hour and a half testing the line and internal wiring and came to the same conclusion as me - buggered exchange/switch. He was from a different town though and didn't have the key to the exchange (or something like that) so he had to pass it on to a more local engineer.

More local engineer rang me at around 4pm to say he had gained access to the exchange but wasn't able/allowed to replace the faulty equipment but it would be sorted tomorrow (today !)

Had a call from yet another engineer today but my phone buggered up and went straight to voicemail. When I'd worked out how to retrieve the message, the engineer had explained that they had fixed the fault at the exchange but identified another fault with the phone line between the exchange and house........

I'll let everyone know the outcome if/when it gets sorted.

Final update.......

Had a couple of texts on Friday to say it was taking longer than they expected etc etc but then nothing.

My Gran had a ring from someone to say there was still a problem but the phone was ringing properly when it happened.

All seems well with her line so my dad put her new phones back on and it all worked perfectly.

So it took 3 engineers and 2-3 days to get sorted but at least its sorted

If he's from out of the area he won't have permission to enter that exchange on his OBASS card (which is the same as your identity card these days). BT are paranoid about letting their own staff into their own buildings - I couldn't get into the 21CN area upstairs despite working in the office in the basement.