3GP is a multimedia container developed by Third Generation Partnership Project in 1998 for GSM-based (Global System for Mobile Communications) phones. The container requires little bandwidth, storage space and data usage that is why it is ideal for cell phones. It is a standard container for the files sent using MMS (Multimedia Messaging Service).

Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end ARM3 processors. Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.