Voip via usb mobile broadband

[SystemParanoia]

i know that in the most marketed packages, in the small print, they claim to not want you using the device for voip services.

my question is, if i encrypt the voip traffice through ssh or a vpn, will it work as intended ( presuming the ssh/vpn terminus has plenty of bandwidth ) or will the mobile broadband provider cotton onto what im doing and cut my service ?

i know t mobile allow you to use voip in their top package.. but thats expensive lol