A first mobile device is provided. The first mobile device includes at least one hardware processor and a first mobile device application, executed by the at least one hardware processor. The first mobile device application is configured to detect that the first mobile device is in physical contact with, or within a predetermined distance of, a second mobile device. The first mobile device is also configured to, in response to the detection, send a switch request to make a mobile phone line inactive for the first mobile device and active for the second mobile device.