Relocating a BT line

[The Natural Philosopher]

From a model airplane site I frequent...

"Hey mate, what frequency are you on?, I'm on channel sixty" "I'm on sixty, too"

CRUNCH.

"Sorry, but you said you were on channel sixty-two"....

[Andrew Gabriel]

Anything which expects to detect the line reversal signals from the exchange (such as those which precede the callerid FSK) would need something more complex than a full wave rectifier input. This is probably partly the reason the first callerid units and callerid modems were rather more suceptable to wrong polarity lines than one might have wished for.

Some hardwired PABX's certainly are sensitive to wrong line polarity. IIRC, it causes them to fail to recognise remote caller hanging up. This might also be due to not seeing an exchange generated line reversal signal (not sure quite what the mechanism is for exchange signalling this back to a PABX).

[Mike]

Some cheap faxes and fax modems don't do ring detect properly and could fail on a line reversal. But who uses faxes anymore ;-)

[Andy Hall]

Don't you have a pegboard?