I recently signed up for Sunrise's talk & more service. They sent me the Zyxel Prestige 2000 VOIP modem, and a new phone number for VOIP. I didn't expect to receive a VOIP phone no. The inconvenience is that my "computer room" in the house is where our upstairs phone with its built-in answering machine is. If I hook the phone up to the VOIP router, it uses the new VOIP number and I can't receive calls from the old no. on the answering machine. I could swap the phone+answering machine with the phone on the main floor, but I'd still lose the ability to answer my "old phone no." upstairs. Has anyone found a setup that lets them phone out on VOIP, yet receive calls on their old non-VOIP no.; on the same handset? Is there some kind of switch/adapter that I could just toggle when making outgoing calls?

I have two separate DECT phones (quite cheap nowadays). I used VOIP number for outgoing calls and the old number for incoming calls. VOIP subscription is free in evenings and weekends.
It will be interesting to know about any switch or adapter for the toggling purpose.