I had to figure out how to interface a small SPDT relay (Radio Shack, PN 275-240) to my PIC, and was able to do a little test and turn on an LED, so I have that working. Now it's just a simple matter of hooking the relays to the the tip and ring lines.

I'm unsure of how to connect all this up to the house phone such that I can dial out with the circuit when I want to, but upon disconnecting from the circuit I regain the house line. It's not clear to me from your schematic, BobK, how I implement that with phone jacks. Any tips?

Thanks.