Ethernet over phone line

I am helping my brother in-law setup a network at home and part of that network involves setting up a ethernet connection of some sort for his father who lives in an apartment above their garage. Since the house isn't connected to the apartment, and I believe gets its own power, ethenet over powerline will not work but they do have a common phone line. I was wondering if anyone new of any good products that work at connecting an ethernet connection over a phone line.

The other option would to be to have a really powerful wireless network but since the garage and apartment are made of stone I'm not sure how good the reception would be.

Any ideas would be appreciated.

Thanks
aslaiby

Is running a cat5e cable out of the question?

You could use a product like this; I have no experience with it... just found it using google.

Phoneline adapter is aim to connecting an ethernet connection over phone line between one apartment to another apartment, it is convenient for neighbour to share the network. you can find it in ww.wondertek.com
i have used it and also introduced to my friend, i believe you will like it, because i do.

This looks like it will be a bit out of the price range of a normal home network setup. You can't even get a price without a real quote from the vendor.