Hello exxtraordinaryyx,
Thanks for using Apple Support Communities.
For more information on this, take a look at:
iPhone: Troubleshooting issues making or receiving calls
http://support.apple.com/kb/TS3406
- Toggle airplane mode: Tap Settings > Enable Airplane Mode, wait five seconds, then turn off airplane mode.
- Check your phone settings:
- Ensure that your software is up to date:
- Check for a carrier settings update.
- Check for an iOS software update.
Note: Some updates may require a Wi-Fi connection.
- If the iPhone has a SIM card, reseat the SIM card.
- If the iPhone 4 or iPhone 4s is on the Verizon network, dial *228 from the iPhone and select option 2 to update the Preferred Roaming List (PRL). The PRL determines the cellular towers the phone uses for cellular service, selecting those with the best signal strength.
- Reset the network settings: Tap Settings > General > Reset > Reset Network Settings.
- Try to make or receive calls in another location.
- Attempt to isolate to one network band:
- If you're having the issue on LTE, disable LTE, if possible, and try again.
- If you're having the issue on 3G/4G, disable 3G/4G, if possible, and try again.
- Contact the carrier to check the following:
- Your account is properly configured to use the specific iPhone that has the issue.
- There are no localized service outages.
- Your account doesn't have a billing-related block.
- Your calls don't have errors on the carrier system.
- Restore the phone as new.
Best of luck,
Mario