I just found this newsgroup and I'm responding to a response.
Apologies if I'm repeating someone else.

In Anchorage, at least one real estate firm uses the radio/tape
arrangement and publicizes it as the "talking house". I've driven by them
a few times and it seems to work. If this is a common real estate sales
tactic, maybe you can find something locally. I'd assume that if they
weren't pretty reliable, the real estate people wouldn't use them. If you
don't have any luck, give me a Email and I'll see what I can learn here.

Regards,
Dick Morris
Board Member/Volunteer
Museum of Alaska Transportation and Industry