Tropos Networks announced its 230-square-mile Wi-Fi network in Tucson, Ariz., supports ER-Link, the nation’s first video-based, emergency medical services telemedicine system. ER-Link lets doctors at Tucson’s University Medical Center use video and telemetry to gain a sense of the severity of a patient's condition by viewing real-time information from Tucson Fire Department ambulances en route to the hospital.