🚀 go-pugleaf

I saw an advertisment for a modem interface that connects to a telephone
handset jack for $99.  It has a polarity switch and a 4-position line-level
switch.  It has two jacks, RJ11 and RJ??, one for the telephone line, the
other for the handset.  Another switch is used to select the handset or
the modem (voice or data).

It seems to me that all that's needed is some line level matching 
transformers to convert from the two-line telephone levels to the 4-line
handset levels.  

Can someone please supply a schematic and parts or is it worth buying?

Here's a rough picture of how this interface box is connected to a telephone:

	  ^.^____^.^
	  |_______\
	  \  . . . \
	  |\  . . . \
	..| \________\
   _    . |_|________|
  (_)   .
  \ \   ............------.
   \ \ _           |      |             .-------.       .----------.
    \_(_)..........| box  |.............| modem |.......| computer |
		   |______|             |_______|       |__________|

Thank you in advance,

Ken Shaffer
modcomp!kshaffer