I missed a call from O2. Was it genuine?

[Dazza4]

I received a text saying I missed a call from o2. Would it have been genuine?

[jonsie]

Were you expecting a call?

Have you asked for your PAC?

Otherwise it's doubtful it was from O2

Best option is to call them

Guide: How to find help & contact O2 

[pgn]

Funny, as the option for a message received by O2 voicemail to be notified to the subscriber by SMS was discussed recently, and dismissed as no longer a thing, @Dazza4 

Take the advice given by @jonsie above!