For all modern line transformers, the description in the e-mail from Gill Simon is not correct. There are two problems:

1) Impedance problems. Without knowing the proper termination circuits you will have tons of (illegal) echo on the line.

2) Modern modem transformers are not designed to handle the DC current and will burn. For these transformers you need to add a DC current holding circuit. and put a capacitor in series with the transformer to block the DC.

3) If you want to follow the description make sure you use an OLD (2400 bps/9600 fax type) transformer or even better salvage one from an old PABX.

Jesper