There are many taxi companies in Barrie & Muskokas area. Some do well with telephone reservations, others have stands at major shopping malls or hotels.
If you are not in Barrie, the city, use a taxi company based in the city where you are staying or visiting... they'll usually be quicker to pick you up.
Most taxi firms can give you an estimate of the fare when you call. Some firms have set fixed rates for specific trips.
Oh, yes, and if your driver was courteous and helpful, it is the custom to tip him (or her)! Tips on tipping.
Find Local Taxi cab companies.