3G2 is an audio and video format developed by Third Generation Partnership Project for CDMA-based (Code Division Multiple Access) phones. Actually it is an updated version of the 3GP file extension. Both formats are based on the ISO base media file format that facilitates presentation and interchange of the media. The 3G2 format is flexible and requires little storage space that is why it is mostly used by cell phones for saving files. However 3G2 movies can be played on computers but in some cases additional applications may be needed.

Continuously Variable Slope Delta modulation is a voice coding method. It is a delta modulation with variable step size (adaptive delta modulation), first proposed by Greefkes and Riemens in 1970