The Public Moble sim card didn't work in my Iphone 4 and so I got a Samsung J3 prime and in worked just fine. I'm not big on upgrading phones either. My husband is still using our LG phone from 6 years ago with a sim from our old provider. Just sugg...
Your phone may be too old. It was thought that my Iphone 4 would work with the Public Mobile Sim card and it didn't, so it may be time for you to upgrade your phone.
This happend to me too. I had an Iphone 4 and it was just too old to support the Sim card. I went to Staples and bought a samsung 3j prime and it worked not problem. Try the sim card in a different phone.
