The disclosure is directed to a mobile communication device that measures characteristics or attributes of a first communications network that vary according to physical location within that first communications network to create a fingerprint, or signature, of a location within the first communications network. When the fingerprint of the current location of the mobile device is created it can be compared to a known fingerprint associated with a second communication network to determine the mobile device's proximity to the second communications network. Furthermore, the second and subsequent fingerprint that are generated for a particular communications network can be used to modify the stored fingerprint so as to refine it to improve detecting the proximity to the communications network.