I fixed it myself with no help from ASUS!!
It seems after an auto update some of my mobile settings changed. I started playing with it and found changing the preferred network type to 2G/3G my phone can make call again.
The strange thing is I still have the 4G icon. I have run speedtests in the network and it is closer to 3G speeds.
Looks like it works but I am somehow stuck with 3G speeds. I will probably upgrade to a 5G plan.