Richard Hayler has written an excellent tutorial on using this new add-on board from Pimoroni. You basically connect to the pHAT using minicom and then send old-style AT commands like you would with an old modem. He hasn’t quite gone so far as to show how it might be used practically as an IoT device, but I suspect that’s not far off. Read it here. To get hold of the pHAT, you can go to Pimoroni or The Pi Hut.