Systems and methods performed by an IP telephony device or an element of an IP telephony system mask the data contained in data packets bearing the media of an IP telephony communication to prevent an Internet service provider from identifying the data packets as carrying the media of an IP telephony communication. The systems and methods can also modify the size of data packets and/or modify the data transfer rate of a stream of data packets bearing the media of an IP telephony communication to prevent an Internet service provider from identifying the stream of data packets as bearing the media of an IP telephony communication.