> The problem with this is it has only been the last couple of years that BT has
> been fitting master sockets, we have 12 ADSL at works (not on one site) and
> only one of them has a master socket where you can take a small plate off to
> reveal the master socket (for testing purposes according to BT). All the rest
> are standard BT phone sockets. Those 12 are a mix of home phone conversions,
> ISDN conversion to PSTN (for ADSL) and new lines put in for ADSL.
<pedant>BT have always fitted master sockets otherwise your phone
would not ring!</pedant>. The newer type of socket with a small
removable plate is called an NTE5, and as you say
Way back when, the only difference between the master and slave was
(as noted elsewhere) the addition of a ring capacitor and a resistor.
Outwardly they both looked the same.
