Signal Bar is full but cannot make or receive calls , when dialing out "connection error" comes , If dialing the number it comes as switched off ....The phone needs to be restarted every time this happens , happens every day atleast once , attempted a factory restore , still the same issue ......Using the same unit for more than a year , now the issue cropped up after the Belle update only.....
Welcome to the Nokia forum.
Hard reset the phone, then reinstall the software to fix the issue.
Make sure you make a back up with Nokia Suite first by going to Tools > Back up. Don't tick the Settings box as this will backup the bug that's causing this. Once you've made the backup, enter *#7370# into your phone and default security code 12345, unless you've changed this code yourself.
Once the phone has rebooted, reconnect it to Nokia Suite and update or reinstall the current software to make sure you really get rid of all possible bugs. You can do this by clicking on the green arrow in Nokia Suite.
After you've done the above, place the backup back onto your phone by going to Tools > Restore in Nokia Suite.
Let me know if this doesn't work so that I can troubleshoot further, if necessary.