Missed calls

[PinkBiker]

Galaxy S8+ approximately 12 months on o2 pay monthly - for some reason Its hit and miss whether I receive phone calls. I can have the phone in my hand and it doesn't ring - yet I get the free text alerts to advise of a missed call.
Mobile signal is perfect and I can return the call no problem.
My phone log does not show a missed call has occurred. If it were not for the free text alert service I wouldn't know someone had attempted to ring.
The caller states they just received my voicemail and it didn't ring their end.
This has happened numerous times now and is getting more frequent on a daily basis to different callers.

Any suggestion whether this is a network issue or a phone/software issue?
The phone is turned off frequently to 're-set' also.

[MI5 · Accepted solution]

Usually a network congestion issue.
The "fault" may not show here http://status.o2.co.uk/ as O2 don't recognise congestion as a fault, so call customer services to report it, often, esp if it gets worse.
http://www.o2.co.uk/contactus

[PinkBiker]

A phone mast is currently down near me apparantly.... Could explain it however, It doesn't just happen at home. It happened today while I was a good 15-20 miles away so highly doubtful it would come from the same mast issue. Will see how it goes anyway, thankyou

[MI5]

Certainly would be the reason at home and coincidentally could be a fault in the other area you were in too.