Beacons can exist outdoors. What will the order of response when a beacon location coexists with GPS based messaging?
The messaging for a beacon will always trump a message from GPS, even to the point of interrupting a GPS based message if playing.
In the battle of GPS vs. Beacon, Beacon wins

The premise is that the presence of the beacon is more accurate and intentionally placed. As such, it is deemed to be of higher priority in the messaging stack.
If you shake (well, shake your device!), this command still overrides everything else in BlindSquare

If there is secondary information, indicated by a tone after the primary message is played, this can be unpacked by shaking the device also. After 10 seconds, it will repeat the primary message.