Odd telephone fault

[tony sayer]

Look up "Vocoder" related to VoIP Dennis....

And the way it works...

[Dave Liquorice]

They would be but I doubt anyone listening would be able to tell a fault unless it was a gross fault like one of the tones being completely abscent. I'd expect that to affect more than one digit as the DTMF pairs are formed from a 4 x 4 matrix so if the 770 Hz tone was missing it would affect 4, 5, 6 and B.

[Peter Parry]

The cause, whatever it may be, is not a wiring fault. Telephone wiring is simple and robust. There isn't a wiring fault which can, on a normal telephone service, stop a single number being called when all others still can.

As others have said - have you tested from all sockets using the same telephone handset? (preferably the simplest on you have).

[charles]

Are you using a number stored in the phone or "dialling" it each time?

[Graham.]

In addition I would suggest that the OP performs this test from an affected phone:

Lift receiver and dial the single digit "1", hang up. Repeat using the other digits including *&#. In each case the dialtone should break (disappear) as soon as the DTMF tone is sent.

My theory is the Openreach engineer has left your extensions connected directly to the line instead of wiring them to the filtered side of the new VDSL faceplate. This will inject noise into the phone, might not be audible noise, but it might interfere with one or more DTMF digits.

[kraftéé]

John you either misread or didn't understand the original poster who stated that they had been 'upgraded' to infinity so they will only have the one filter on the NTE (or should that be in the NTE) and do not require any others.

As for possible solutions I wouldn't like to theories about what could be causing the problem as the only problem I have come across with the SSFP which are being used for NGA have been when they go HR/Disconnected nothing to do with the actual signaling/dialing a number.

[Geoff Pearson]

I get the number unobtainable tone then a a female voice says " Sorry, there is a fault" and disconnects. I have indeed swapped all the phones round - I have 4 identical BT Decor phones. Dialling the number successfully is possible only in the phone socket of the NTE5 - which is the new Infinity one with a built in VDSL socket. When that number calls me the phones recognise the number and show the caller's name but I cannot return the call. I thought it was because I do not permit my identity to show but my phones are set to dial 1470 for stored numbers and I have tried dialling with 1470. Logically it is something to do with ten wiring that affects all the extension. BT Fault people say they have done something and it is fixed now, but it isn't. I will just rewire my extension system - luckily there is 5 feet below my ground floor for crawling.

[Geoff Pearson]

No - I don't need filters now as the Infinity master separates it all at source.

[Geoff Pearson]

As note above - I have 4 identical phones and when I rotate each one to the master the problem is gone. Only when connected as extension is there a problem - and it is the same for all three.

[Geoff Pearson]

A number stored, the same number dialled direct, the same number dialled prefaced by 1470 to release my identity. I call dozens of other numbers - they all work.

[Geoff Pearson]

I can see the extension connection internally connected to the Infinity face plate - it is my cable so easy to recognise. There are three Kone connections and the extension link is connected to the top and bottom ones - leaving the middle one empty. There are only three.

[charles]

[Snip]

So, you are saying the extensions are plugged into the Infinity outlet?

If that's true, try plugging some other extenson - such as a wind up drum into the outlet instead.

If not , BT shouldn't have wired it like that.

[NY]

Whose responsibility is it if BT wired the extensions to the faceplate of NTE and made a wiring mistake? The fault only affects the extensions, not the NTE, but the error was made by BT.

By rights it should be BT, but I bet they have some sort of exemption against this - or claim that the customer had later made unauthorised modifications.

[NY]

Are you able to switch a phone to use pulse dialling and see if it's still affected?

I wonder what DTMF signals the exchange is actually receiving and why the fault only affects one specific dialled number - maybe the presence of a digit (or a pair of digits in sequence) that by chance only occurs in that number and not in any others that you dial.

Did the fault exist before the sockets were changed for VDSL and Infinity, or had this already been done before you moved in or first tried to dial the affected number?

[Geoff Pearson]

No - the Infinity outlet provides a Broadband outlet on the main plate and a filtered phone socket on a detachable face plate to which the extensions are hardwired on the back. My self installed wiring of 20 years ago has the bell wire connected but that no longer matters as there is no DSL signal on that set of cables. The VDSL signal travels separately on CAT5 to my hub which is 7 metres away from the master socket. The BT Infinity installer just transfer my hard wired extension from the old NTE5 to the new Infinity one - he didn't leave the locality of the main socket.

[John Weston]

Sorry, I missed this essential word :-)

[John Weston]

OK try this one, now I've hopefully read it correctly... :-) Check if your extension wiring has been reconnected so the wires previously going to 2 & 5 on your extension sockets now has one of them going to 3. Check each of the wire pair connected goes to the same socket connections on the slaves as in the master - and is a good connection with the punch- down done on a fresh part of the wire. What colour are the phone wires in the Master and the Slaves?

I've know a DTMF generator that couldn't cope with long numbers. It's power supply was fine at the start whilst a capacitor was charged, but when that charge was "used" it didn't like it. Could this be happening with the ring capacitor if your wiring is now incorrect?

[George Weston]

A radical solution - but cheaper than getting an Openreach call-out charge: Ditch the internal wiring entirely and buy a DECT system. They're surprisingly cheap lately.

[dennis]

I don't need to, why don't you explain to the rest now you have introduced it.

[S Viemeister]

That's what we did.