Land line phone not working puzzle

[neate]

I have a BT DECOR 1200 land line phone. It is connected to the BT box with an ordinary 5m BT cable that has four brass contacts within the different connectors at each end. It works fine.

I disconnected the cable from the BT socket and phone. And connected up the phone with a 1.8m brand new BT cable (with four contacts). The phone did not work ie has no dialling tone. I tried another new cable with no success.

How can this be. Any help would be appreciated.

 

[rsgaz]

How can this be.

Some older phones use pins 1 and 4 in this diagram...

Modern equipment uses pins 2 and 3. You can check this with a multimeter.

 

[neate]

Thanks rsgaz I'll bear this in mind.

 

[OwainDIYer]

British plugs (with the latch at the side) use pins 2 and 5. American plugs use pins 3 and 4. (Both count the positions in a 6-position shell even if it only has 4 contacts.)

Some BT-US cables are straight-through, and some crossover and swap pins 3-4 with 2-5. Whatever new cables you've got, you need the other sort.

 

[neate]

Sorry its taken so long to get back touch OwainDIYer. Thanks but I have BT cables only. Since posting I have expanded the problem I have. Here goes.

I have a BT land line socket box located inside my hall. Through a hole
in the interior wall an ordinary BT 5m cable that has four brass pins
within the different connectors at each end goes from the BT box through
this hole to my BT DECOR 1200 phone. It has a dialling tone and works
fine. And so does a new BT DECOR 2500 I recently bought.

I decided to put the BT DECOR 1200 land line phone in the hall and used
a double adaptor one for the next door phone and one for the hall phone.
The BT DECOR 1200 did not have a dialling tone and obviously doesn't
work. But the BT DECOR 2500 did still work in the room next door.

I tried using the BT DECOR 2500 in the hall and used another BT cable
with four pins from the hall BT socket, there is no dialling tone. It is
the same with a BT cable with only two pins either end. Both are new
cables. And I have used a multimeter to confirm that there is connection
between the connectors at either end.

It seems that both my BT phones are wedded or paired or allied to this particular cable.

How can this be. The only thing of consequence was a terrific lightning
storm recently which caused land line internal socket boxes nearby to be
replaced by BT engineers. Our land line apparently survived but with the
problem described above.

It just doesn't make sense. Any help would be appreciated.

 

[OwainDIYer]

So both phones work on the old cable, but neither phone works on either new cable?

Therefore both new cables are either faulty or the wrong type. Did they come with the phones or separately?