Telephone

[Crackle]

It depends on if you have the newer type BT master socket. https://www.youtube.com/watch?v=DaKTUF4UoEI

This is designed so that you can fit as many extension sockets as you like. The maximum load on the BT line during the ringing cycles will be governed by the capacitor hidden in the non removable part of the socket.
Mike

[ed731pdh]

Our master socket and extensions are surplus to requirement now that the house phone line is voip'd over FTTP. Downside is that because it is all fibre the modem has to be powered from the house end of the line, all well and great until you have a power failure on which the battery backup systems give just over an hour of operation before it winds down. As with most things, the designers don't seem to think that you have power interruptions as you all live in towns, but as someone out in the sticks, power blips are often a royal pain.

Back to copper systems, it is now recommended to leave connections 3 and 4 disconnected if you have ADSL as it apparently can cause speed issues due to noise interference.

As to standard BT fare, I was doing an extension once at a friends house, putting in extensions, every time I connected up the bells in the house started to tinkle, even with no phones plugged in. Fault was eventually tracked to a sub socket (obtained that very morning from Maplin) that on taking apart was found to have a solder whisker between pins two and three. So much for quality control.