Hi @homediy,
I never thought I'd see another one of them sockets again!
They're the older type Austel sockets from the 70's/80's, back when people had to have a technician come in and make any changes to your telephone wiring and install a new point for a second phone.
First question is, do you still use a land-line phone?
Second question is, if so, do any of your phones use connectors like these?
Is this system still hooked up in any capacity within your home?
Usually these days, for a landline, you would have what is known as an RJ-12 connector that the phone plugs into.
Back in the day, the POTS (Plain Old Telephone System) used to use a 50 Volt DC feed from the exchange (fed from batteries), this was for the ringer signal used with with bell type ringers in the same era of rotary dial systems, when you picked up the receiver, the voltage would drop from the 50V (on-hook) to about 25V (off-hook).
If you have a multimeter, just check between all of the wires to make sure there is no voltage present, if there is 50VDC present, you need to trace that cable back as far as possible and disconnect it at it's point of supply, the current is miniscule, in the area of 1 milliamp so there is no chance of this being any sort of a shock hazard.
There should have been 3 wires connected originally, one was the return (which from very hazy memory was black), the "Tip" wire was blue and the "Ring" wire was white.
By rights, there should not be any voltage at all between any of these wires, if the socket has been disconnected.
The POTS system is way outdated, I disconnected my landline ages ago as everyone uses cellphones these days, my landline only rang if it was tele-marketers and spammers.
By all means, let me know how you get on with this, if you require further advice, I'm more that willing to help you out, especially with something like this, not a lot of people know about or understand how the old POTS system worked and merely cutting wires could cause all sorts of problems.
Cheers,
Mike T.
