Emergency Mode displays on many Sprint phones after a 911 call. This mode is designed to prevent outboundcalls keeping the phone open for emergency communications should it be required.
To make your device exit out of emergency mode remove your battery for approximately 30 seconds (or power off device for one minute if battery can not be removed), replace battery and power on device. Finish by pressing *#119# or #*119#on the keypad. This will take your phone out of emergency mode allowing you to be able to make and receive calls as normal.