It might be worthwhile joining the RATRING group at Yahoo. This is run by Ken Boakes and ex- BT phone engineer and the whole= group specialises in PIC s and interfacing them to the telephone= lines. I don't recall what your attempting appearing as a topic on the= list but you might find a like minded person there. Plus how to= isolate your equipment (line transformers) from the phone line, gyrators= and other such things. There is a web page but I can never remember it's URL. Colin -- cdb, bodgy1@optusnet.com.au on 24/09/2002 -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads