A mobile device can monitor a current location using a multi-tier approach. A baseband subsystem can monitor a coarse location of the mobile device using various course location parameters, such as a mobile country code (MCC), a location area code (LAC), or a cell identifier (cell ID), as the mobile device moves closer to the geographic region. Upon determining that the mobile device is in a cell that intersects the geographic region, the baseband subsystem can transfer the monitoring to the application subsystem. The task can be performed when the application subsystem determines that the mobile device is currently located in the geographic region. A beacon network can provide more accurate estimates of mobile device location and advertise location based services available to the mobile device.