According to the advisory, Google's (NASDAQ: GOOG) Android platform does not have appropriate permissions security for LTE networks, especially for VoLTE, and also suffers from improper access control. "Some networks allow two phones to directly establish a session rather than being monitored by a SIP server, thus such communication is not accounted for by the provider," the advisory states. "This may be used to either spoof phone numbers or obtain free data usage such as for video calls."