I recently moved my copy of outlook 2016 Professional to a new computer. After install, I called Microsoft to register the license to the new PC (having uninstalled the old PC). I chose the automated option, called the MS number and chose the online option. I was sent a message to my phone with the URL to enter my current set of registration numbers. The url brought up a screen with a 9 key entry page. That's right, it had the digits 1 thru 9 with not zero! As I have an older android phone, I tried the url on my wife's more resent Samsung with the same results. Finally I chose the voice option, and read the 40 or so numbers to the MS app, which then read back to me the appropriate digits to validate the license and I am now registered. I hope this info helps others who run into a similar issue.