It is pretty good at predicting if a CHAdeMO unit is working.How accurate is the Electric Highway app when it says a charger is available/ready - does that mean it will work including full comms with the my account to pay etc. ?
If the charger looses comms it defaults to free vend. In this case your phone won't be able to start a charge, but you can start a free charge from the buttons on the charger.
There is no way for them to know if your phone will work. If your mobile data isn't working, there is local WiFi right at the rapid. You should ask EH on twitter for the password. I've used it a few times when my phone couldn't get a signal.