I’m fairly sure I read a post where someone put their phone back into the copper master socket to test if those calls not getting through on DV ‘rang’ the copper pair line ( they did ) , the issue effectively went away after a short while , presumably some of these networks ( non BT/EE mobiles , other landline networks, Sky, TT etc ) are slower in starting to route calls made by their customers to the DV ‘address’, it seems not all operators action this change at the same time , but in the example I recall, it was a short lived problem, you could try that yourself , especially if you have a second corded phone .
