Change Mac OS X Wireless Card Country Code
802.11d is the protocol that wireless access points use to broadcast (among other things) the regulatory domain (i.e. country codes) in which it is supposed to be operating. It seems that there may be no clear rule for what to do when various equipment is broadcasting conflicting regulatory domain information.

The ideal solution would be to disable/replace/reconfigure the equipment that is broadcasting the incorrect information.

I found an (oldish) Apple Discussions thread that indicates that indicates that a Mac’s AirPort hardware will use the first country code it hears after powering on or waking from sleep. Later postings in the thread (on the second page) indicate that it is sufficient to just power off/on the AirPort hardware itself and not the whole system. A couple of people reported success using a script to repeatedly turn the AirPort interface off and on (using networksetup) until it happened to acquire the desired state (as reported by system_profiler).



Based on TA25972, it seems that older equipment (presumably models that do not listen for 802.11d information) may not even be able to switch “country codes”.