A method includes communicating, by an application executed by a processor of a first mobile communication device, with a server system. A first phone number corresponding to the first mobile communication device is determined or verified based on the communicating with the server system, the first phone number corresponding to a particular shared operating plan enabled by a particular mobile operator. A request is transmitted to a computing system corresponding to the particular mobile operator for a second phone number corresponding to a second mobile communication device and corresponding to the particular shared operating plan of the first mobile communication device. The second phone number is received from the computing system. The processor of the first mobile communication device determines user identifying information corresponding to the second phone number based on data accessible via the first mobile communication device, and the user identifying information is provided to a user.