iDEN is a TDMA-based digital wireless standard designed to work in special frequencies originally designated for analog Specialized Mobile Radio (SMR) networks. iDEN was invented by Motorola, who remains the primary manufacturer of iDEN devices.
iDEN provides several unique features, including integrated push-to-talk (PTT) walkie-talkie capability.
iDEN is used in the U.S. by Nextel and Southern LINC.
Newer iDEN phones use a SIM card that is compatible with GSM phones for overseas roaming. However, iDEN is a very different standard from GSM. Most iDEN phones are not compatible with GSM networks, and GSM phones are not compatible with iDEN networks.