do you happen to have an airave at your home? or possibly a neighbor? you will usually hear 3 beeps when you call out so you know youre connected to the airave. always a possibility.
does this only happen at one place or everywhere you go?
I do not have an AirRave. Had to do this update when installing latest iOS. Also had to do it again after sprint pushed "new carrier settings" to my phone. Won't make that mistake again.