I've just picked up a Nokia 8 Sirocco to use with my Virgin mobile SIM, I get decent 4G signal and mobile data works fine, but when I try to make a call the signal bar drops down to nothing and the phone reports 'no network available'. I also cannot receive calls under 4G.
I've tried a Three SIM and a Tesco mobile SIM in the same phone and they work fine - they automatically drop down to 3G to make or receive the call.
There aren't many settings available to me in the >Network & Internet >Mobile Network menu, But if I manually change Preferred network type to 3G the phone can make and receive calls without an issue.
The Virign SIM works fine in my Nokia 9 Pureview handset. When I go to make or receive a call, it automatically drops to 3G and then returns to 4G after the call. I have checked the Mobile Network settings in this phone and they are identical to the Nokia 8 Sirocco.
I have tried a network reset and then a hard reset on the phone and get exactly the same issue.
I found a discussion on a Nokia forum that suggested that the mobile operator should be able to fix this. My options are currently to leave Virgin or to return the phone.