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[daveesh1]

Just had a thought may be a daft one. If the bt line coming into  my master socket was the wrong way round i.e A&B reversed could this cause any issue on FTTC with speed or errors

[Dray]

Probably not, but it may prevent your phone ringing.

[NewtronStar]

It does not matter which way round you connect them all that matters is that both have a good solid connection to the IDC or screw terminal.

If one terminal is not connected the phone will ring but no broadband sync on modem

[daveesh1]

ok cheers

[roseway]

If one terminal is not connected the phone will ring but no broadband sync on modem

It's the other way round. If one side of the pair is disconnected the phone won't work at all, but you may get broadband sync at a much lower speed than normal.

[licquorice]

Older dropwires aren't even colour coded anyway, so no way of telling which is 'A' and which is 'B' . The only time it mattered was in the days of 'party lines' when one line rang on the 'A' leg to earth and the other on the 'B' leg to earth.

[NewtronStar]

If one terminal is not connected the phone will ring but no broadband sync on modem

It's the other way round. If one side of the pair is disconnected the phone won't work at all, but you may get broadband sync at a much lower speed than normal.

Sorry i have to disagree if you remember back to my BT80b install I put the one leg into A and the other leg into Earth phone worked but no BroadBand sync.

[Dray]

Not connected is different to connected to earth

[NewtronStar]

Not connected is different to connected to earth

The earth wire is not connected from BT80 to master socket so it's an open circuit you have only 2 wires coming in A & B if you connect one leg to earth it's the same as just one leg connected to A or B.

[burakkucat]

Sorry i have to disagree if you remember back to my BT80b install I put the one leg into A and the other leg into Earth phone worked but no BroadBand sync.

I remember that event. 

If you think about the circuit which resulted, you had a series connected inductor (with a minimal resistance) in one leg. That minimal resistance was well within the operating parameters for telephony and the inductance had no significant effect in the voice frequency pass band (300 Hz to 3.4 kHz). Hence the telephone worked. However the inductance was sufficient to perturb the VDSL2 circuit such that the transceivers (one in the modem, one in the cabinet DSLAM) were unable to achieve synchronism. The DC continuity of the circuit was maintained, the AC continuity of the circuit was acceptable for telephony but the AC continuity at VDSL2 frequencies was non-existent.

Now consider the hypothetical case where one leg of the pair becomes detached at the pole top DP (where the drop cable is connected to distribution cable). There is no DC continuity whatsoever, hence the telephony service is interrupted. However the VDSL2 service will "just about" operate in a highly degraded state. Why? A VDSL2 circuit (or any xDSL circuit, in the general case) consists of a pair of radio frequency transceivers normally linked together by a "balanced feeder". Call it a RF transmission line, if you like. When one conductor of that transmission line is disconnected, the RF signal will pass through free-space -- just like any radio transmission -- and induce a signal in an "aerial". In a way, you have a pair of transceivers operating via a pair of aerials (the two ends of the disconnected wire) in a very inefficient fashion. So the broadband service can operate in a severely degraded state. 

Which is my verbose way of saying that Eric is correct . . .

[NewtronStar]

Which is my verbose way of saying that Eric is correct . . .

What I am saying is that i'm correct in what happened on site in my premises not anything to do with drop cable or pole 

[roseway]

Nobody is disputing that what you say happened to you did happen. But we are talking about a different situation here. You said:

If one terminal is not connected the phone will ring but no broadband sync on modem

Sorry NS, but that is not correct.

[c6em]

All my faults are 'single line dis'
That is to say 1 of either the A or B wire in the line pair fails.

The result is always the same:
1 No phone dial tone and I am unable to ring out.
2. Incoming callers get the system generated ringing tone which goes on forever and my phone does not ring and they know that my line has failed (yet) again as my answer phone does not pick up.
3. The broadband drops to a low sync of maybe a few 1000kbps and continues to work at download speeds in keeping with the sync.

[NewtronStar]

If one terminal is not connected the phone will ring but no broadband sync on modem

Sorry NS, but that is not correct.

It is correct I wired it up the phone worked the broadband didn't then remove the second leg B from earth and put into the B terminal and the broadband worked.

Thats a clear case if one terminal is not connected the phone works and broadband won't 

[Black Sheep]

Only just come across this thread.

I can say quite categorically, with just one wire connected (be that A or B wire), the phone will not work at all. The Broadband will work, but will be very slow compared to it's usual speed.