a first mobile , wireless communication device including a memory and a communication module . the memory is configured to store data associating a first user of the first mobile , wireless communication device with a second user of a second mobile , wireless communication device . the communication module is configured to , based on the data associating the first user of the first mobile , wireless communication device with the second user of the second mobile , wireless communication device , establish a communication link between the first mobile , wireless communication device and the second mobile , wireless communication device . in response to the second user being within a predetermined range of the first user , the first mobile , wireless communication device is configured to automatically receive , via the communication link , notification that the second user is within the predetermined range of the first user .