Please be aware that this app can only be used to lookup U.S. base Ham callsigns. The free callsign lookup services available to this app only contain callsigns of U.S. based Ham operators. There are other non-free apps that can lookup international callsigns. If that is your requirement please pay for one of those apps.
The users location can be determined by either GPS (the device's location services) or by using the user's callsign (the address on file for the user with the FCC).
The "other" ham is identified by their callsign. HamRadioCall looks up the other ham's address on file at the FCC and displays that ham's location on a map with the connecting great circle arc. The range and azimuth to the other ham is also calculated and displayed. This can be valuable for antenna aiming and the evaluation of the propagation conditions and the performance of the both ham's equipment and antennas.
HamRadioCall is developed by Roy Watson, N1ZTL. The FCC license data is updated daily and provided courtesy of Josh Dick, W1JDD though an API at his website: callook.info.
PLEASE BE AWARE THAT THIS, NOR ANY OTHER APP/WEBSITE, CAN PROVIDE ACCURATE LOCATION INFO FOR ANY HAM WHO CHOOSES TO USE A PO BOX AS THEIR ADDRESS ON FILE WITH THE FCC. FOR THOSE HAMs THAT CHOOSE TO USE A PO BOX AS THEIR ADDRESS OF RECORD WITH THE FCC, GOOGLE MAPS WILL MAKE A BEST APPROXIMATION BASED ON THE CENTROID OF THE ZIPCODE OR CITY NAME.