Global System for Mobile Communications (GSM) is one of the standards used for mobile phones. Gaussian Minimum Shift Keying (GMSK) is a type of continuous-phase frequency-shift keying used in GSM. Enhanced Data rate for GSM Evolution (EDGE) is a digital mobile technology used in conjunction with GSM to provide packet-switched applications such as internet connection. EDGE additionally uses 8 phase-shift keying (8PSK) as part of the modulation and coding scheme. Mobile handsets using such technologies use power amplifiers and derive power from a battery.