This circuit enables automatic switching-on of the tape recorder when the handset is lifted. The tape recorder gets switched off when the handset is replaced. The signals are suitably attenuated to a level at which they can be recorded using the MIC-IN socket of the tape recorder.
http://www.electronic-circuits-diagrams.com/telephonesimages/telephonesckt7.shtml
it will record any conversation on any phone on same line.
http://www.aaroncake.net/circuits/phonetap.htm
telephone recording, telephone line to mixer and telephone hybrid circuits.
http://www.tkk.fi/Misc/Electronics/circuits/teleinterface.html
allows you to connect any tape recorder that has a mic and remote input to a phone line and automatically record both sides of a conversation when ever the phone is in use.
http://home.maine.rr.com/randylinscott/mar98.htm
lets you record your phone conversations automatically.
http://www.aaroncake.net/circuits/phonrec.htm