Questions about cell network time/date and 'automatic' time set

I set a couple of phones to 'automatic' 'get time from network' yesterday. One Vodafone samsung android, one Telecom $30 nokia. I restarted both phones, an hour later no change to the incorrect time on both devices.

No doubt there are differences in networks and implementations on specific phones but I'd appreciate an overview of how this all works in practice and any network specific information. I realise this is not NTP.