There is *no* other coverage of PayphoneGo that I could find, beyond this Guardian piece and Norris' own LinkedIn post from today mentioning that piece.
On the other hand, there's lots of coverage of Payphone Tag, an Australian game launched earlier this year (April?), by Alex Allchin.
payphonetag.com
A real-world territory capture game using payphones. Dial in, enter your PIN, and claim payphones across Australia to build your turf.
