In article , Geoff Pearson wrote: }Since the man installed BT Infinity I have been unable to dial a specific }number 01631****** on any extension phone. It works on a phone in the master }socket but not the other three. I can dial this number on my mobile. So }there is a subtle fault which affects the extensions - which I will have to }fix under the house. Before I go down under, does anyone have any ideas why }this one number is affected? I have no problems with any other number.
I didn't see anywhere in this thread where you said what happens when you try dialling that number. Does it wait as if there are too few digits, give an announcement, or something else?
It's possible that some digit cannot be detected. While it may seem impossible, given that each digit is composed of two tones, in theory there could be one digit which fails to be detected. This is because a signal is not considered a digit even if it is composed of two frequencies if the amplitude of the two frequencies differs too much. So, for example, a 697Hz tone combined with a sufficiently louder or fainter 1477Hz tone would not be considered to be a valid digit '3'. Suppose your phone generates the high tones barely loud enough compared to the low tones, then adding a slight impairment which attenuates high frequencies more than low ones could result in the furthest-apart pair (697+1477) failing to be detected.
Similarly, if your phone generates one particular high tone a bit quieter than the rest and one particular low tone a bit louder than the rest, that particular pair may fail to be detected when all other pairs are detected (presumably a change has made all tones slightly worse, but this pair alone fails because it was always worse).
However, this all assumes that the failure to dial is as a result of a single faulty digit. If this is the cause, it should be easy to tell which digit is failing.