You can also get converters to adapt most foreign phones to USA wiring. However, the internal connections vary from one country to the next. Some English phones may need a capacitor added to make the bell ring, since the bells would have been originally wired in series between a number of extensions, with one capacitor serving all of them. For more, search under "Tele. No. 706" and follow the links...
Re. phones in the bathroom: You can get do that with older USA telephones of the standard (WE/ITT/SC 2500 or AE 80) or Princess (AE Starlite) types, but the humidity may cause trouble with newer types. On phones with modular cords, humidity may cause intermittent loss of transmission or reception; this is easily solved by cleaning the contacts on both ends of the handset cord, and in the modular handset jacks on the base and the handset, with a Q-tip moistened with rubbing alcohol. Note, when cleaning the mod jacks on the phone, take care to not get the cotton from the Q-tip caught on the back ends of the modular contacts.