Abstract: Advanced mobile personal emergency response systems. An activator worn or carried by a user sends a medical or security alert to a portable mobile base station. The mobile base station transmits the alert to trained operators at a call center. An operator conducts one-way or two-way voice communication through the activator with the user during the emergency response. The mobile base station transmits current location coordinates to the operator, including the last known good coordinates when the user enters an area where the external location system does not work. Emergency responders can use a beacon function to locate a lost activator if they find the mobile base station. A voice quality self-test function is useful for increasing the user's confidence that the system is working. Users can employ a finder function to find one of the activator or mobile base station when the other device is available.