Cellular Message Encryption Algorithm
In cryptography, the Cellular Message Encryption Algorithm (CMEA) is a block cipher which was used for securing mobile phones in the United States. CMEA is one of four cryptographic primitives specified in a Telecommunications Industry Association (TIA) standard, and is designed to encrypt the control channel, rather than the voice data.
Source: Wikipedia — Cellular Message Encryption Algorithm (CC BY-SA 4.0)