Iphone 4 won't send texts or make calls?

I'm on vodafone and it says that i have full signal at the top but i can't send texts or make calls at all, it won't even connect to voicemail, i've tried turning the phone off and on again but nothing seems to work, anyone know how to make it work, or anyone else had this recently?

Hold the home button and hold the power button down together and wait for the phone to turn off… Keeping your finger on the home button… This reboots the iPhone… It sometimes works!

It may be a fault with the network in your area. If so, we will log it on our Faults Board here https://forum.vodafone.co.uk/t5/Services/ct-p/1

If you can't find anything logged, follow the troubleshooting steps here

If you need any further help, you can contact me personally here https://help.vodafone.co.uk/system/selfservice.controller?CMD=ESCALATION_REQUEST&PARTITION_ID=1&CONFIGURATION=1000&COUNTRY=us&LANGUAGE=en with WRT135 in the subject.