Do not post your email in a forum. you will get spammed.
Telephone lines are already just split to the jacks in the house and most desktop modems include a passthrough to connect a phone. a splitter for 1 Jack to 2 is maybe a Buck. Of course you can't use the phone while on dial up, as always. Some ISPs/modems did support call waiting to put the modem on hold and let an incoming call ring though.
I am of course assuming you mean a dialup modem in the laptop. if you are referring to a DSL or cable modem and a VOIP phone you must use a network switch.