Callers get number not recognised message when I’m out of signal.

Same here ​@James.dayment. It’s been hit and miss here for around 2 months.

Mine (as in callers telling me) started around the time 3G was turned off in my area. In other parts of the country its perfectly fine, but I know for me its a local network issue.

I even answered an incoming call earlier today and upon putting the phone to my ear I got the  sorry the number you are calling is not available please try again later.

And yes, also callers have had the sorry the number you are calling has not been recognised

Also had the it's not been possible to connect your call please try again later.

BUT in every case for the above they called me!

My phone can sometimes eventually ping a missed call, though for today’s that was after I ended that dual incoming and outgoing call and called them back.

Like you I don’t always know as there’s not always a missed call notification.

I have noticed that some outgoing calls (saved contacts) don’t always ring either

What causes it, AFAIK, is when our phones drop completely off the network.