In the past we have gone to Walmarts and bought the cheapest phones (pay-as-u-go) we can find and use them, this also allowse us to contact are american friends who live in the area.
It appears to me that the "kiosks" for off-site guests is similar to what UNI started with , when they first started using express pass, they used to be in UNI/IOA and you could pick between 2 or 3 express passes for later in the day. UNI removed them and started charging for there express pass.