call forwarding issue iphone 8
Hello, I cannot activate call forwarding on brand new iPhone 8... After going to : Settings - Phone - Call Forwarding and selecting call forwarding button which goes green and then typing Forward To phone number and then going back , the following 2 things happens :
either
a) Call Forwarding button stays green, but there is no any number remains on Forward To
or
b) Call Forwarding button just deactivates (returns to grey)
I really don't think its a carrier issue - as I have other 2 iPhone's - iPhone SE and iPhone 6s Plus - they are on same service provider network and call forwarding function works perfectly on both of those other iPhone's.
Any advice... ? Thank you !
iPhone 8, iOS 13