Wow, nice!
What happens when you type in your temporary or original phone numbers without an account, or with an account? Thanks
No idea, just saw it and thought I post it here for awareness.
The site says it will send you a SMS, so you would need to input your active number (for most would be their temp Chicago #). It then sends you a SMS that would download their App from iTunes/Google Play/etc and configure your phone. Freedompop has something to adjust your APN on iPhones (when using the AT&T based LTE SIM).