Fishbowl is a mobile phone architecture developed by the U.S. National Security Agency (NSA) to provide a secure Voice over IP (VoIP) capability using commercial grade products that can be approved to communicate classified information.
[1] The initial version was implemented using Google's Android operating system, modified to ensure central control of the phone's configuration at all times.
To minimize the chance of compromise, the phones use two layers of encryption protocols, IPsec and Secure Real-time Transport Protocol (SRTP), and employ NSA's Suite B encryption and authentication algorithms.
USMobile[2] has implemented commercial enterprise version of Fishbowl technology via the Scrambl3 mobile apps that run on both Android and iOS platforms.
[4] These Protection Profiles list out the requirements a commercial product must meet to be used in the mobile phone architecture.