Hi,
I can suggest these generic self help tips.
On the iPhone hold down the Sleep/Wake Button and Home button together until the Apple Logo shows. Then On seeing this Apple Logo release both buttons ,and the iPhone will reset , which has been known to clear most glitches.
Other options are :
Settings -> General -> Reset -> Reset Network Settings.
Plz try ure Sim in another phone as a process of elimination 2 rule out the phone or sim that may be at fault. If another alternative phone takes a different size sim then ask for a sim adapter which is a plastic slip that makes the nano sim temporarily into a standard or micro sim.
Check that your masts are fine by
https://www.vodafone.co.uk/explore/network/uk-coverage-map/index.htm or does this happen everywhere ?
Try hooking up to iTunes and make a back up to iTunes and or iCloud and Restore.
If your sim works in another phone then if you have an store local make an appointment via
https://www.apple.com/uk/retail/geniusbar/ and they'll typically repair or swap it out for a replacement if under one years warranty. Make a back up to iTunes and or iCloud before you attend the appointment.
Try another vodaphone sim perhaps a Payg one or a friends Vodaphone SIM card to see if it works.
If it does then speak to Vodaphones customer services to have your account Reset.
Check your not awaiting any carrier updates via checking
https://support.apple.com/en-gb/HT201270Good luck
😎
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.