Optoisolation for a modem

Does anyone know of a good way to protect a modem from spikes on the phone
line? The Triplite surge protector works once, then the next jolt cooks the
modem. We went through three modems and a fax machine last year. Bear in
mind that we almost always unplug the modem after each use. It's those rare
"almost's" that cause the problem.

Our power is relatively surge free, probably because we have MOV's on three
circuit panels and three wall outlets. Haven't blown one of these yet. The
Triplite phone line protectors are just too expensive to replace as often as
they go bad here. And they only get the first blast. The modem gets the
rest.

We live on a lake, so lightning is a problem. Any suggestions, such as
optoisolation?

Doug