Hi ​@Richard Billany 

Thank you for getting in touch with us, I am so sorry that you have no signal please try the following steps:

Please use the following link to check the coverage in your area:
https://www.idmobile.co.uk/help-and-advice/coverage
or try to reinsert your SIM, or try your SIM in another phone. This will determine whether the issue is with the handset or with the SIM card itself.

If the issue persists, please try the following steps for iPhone:
Go to Settings.
Tap Phone.
Tap My Number.
Use the delete button to remove the old number.
Use the keypad to enter the new number.
Tap Save.
1. Go to Settings
2. Messages
3. Turn off iMessage.
4. Go to General
5. Reset
6. Reset Network Settings.
7. Once the iPhone is open.
8. Go to Settings
9. Messages Turn ON iMessage.
10.This will recognize the new sim and have it verified.

Network settings for Samsung:
Go to Settings
Tap General management
Select Reset
Choose Reset network settings
Confirm by tapping Reset settings

Thank you,

Zandile