How about answering the phone with a Shinui – i.e., pushing the button with a knuckle or the like? The main Issur with a phone is making the connection, not speaking once it’s made. Considering that (a) according to most Poskim, electricity for uses other than an incandescent bulb is a derabanan, and (b) answering with a shinui is also a derabanan, it would seem that that would be preferable to having someone from Hatzala possibly do a deoreisa by driving over.
an Israeli Yid