Ive seen in other threads members having issues with the same phone and it was related to the 8.1 software on the phone...I suggest starting a new thread with your phone model in the title and help wont be far away..
I moved my public mobile sim card from my old phone to a new Asus Zenfone max Plus (M1). However, I am not receiving any phone service and not able to connect. WIFI does work. The SIM card toggles on and off and is unavailable. The PM SIM card works well in my old phone and other SIM cards from other providers work in my new ASUS phone. However, my Public mobile SIM does not work with the Asus Zenfone max Plus (M1). I've contacted ASUS and they said the issue is not with the phone but with the provider PM. Any suggestions?
If yoru Zenfone Max Plus M1 is the North Amercian variant, Asus is full of it. This would be completely a phone issue. Even ifyou have a non-compatible version of the phone (this would be a non-North American version), this would still be a phone issue. You've already determeind that the Public Mobile service is not issue by trying it in another phone.
There have been reports of the most recent update for these Asus phone breaking the connection to the network, not only the data abilities but the connection to the network itself. This has nothing to do with Public Mobile and is 100% on Asus.