Any one heard of such a device?  

I've heard of dialmate, a product that lets you do a three way with
your home line.  You call home line, enter a code, dialmate wakes up,
you enter 2nd "to call number", It puts you on hold by (by using your
home line 3way) calls number you entered and, then puts you back on
the three way.

Some cellular providers let you use your home number as part of a
"family plan", having unlimite calling to it.  I think this product
described above is a little retarded, and I'd like to access the 2nd
home lines dial tone directly and make calls off it.

Anyone know of such a product that can access this 2nd home line
directly, and make calls from it?

Thanks in advance
Stu