Off-topic informational anti-spam anecdotal

< Ok, so given that there are people out there who know about phone < systems, how would I build a device that sat on the phone line and could < detect whether the line was in use or not - it's extremely annoying when < you have a modem and voice phone on the same line and your voice call < gets interrupted by a burst of modem noise! :) for this the US and euro systems are sufficiently the same. < < btw, this is for a UK system - I've seen curcuits to do exactly this < job, but they never say whose phone systems their designed for, and I'd < imagine that US and UK systems work with different setups.... the only thing you need to do is detect if the line voltage is above or below some level. that point is best set mid way between battery off hook and battery on hook (easily measured). The only other need is to do it such that you do not load the line(or you look like your off hook) and can withstand the ring without failing the circuit. Likely the circuits you've sen will do that. Allison