Hi ​@Brenmeister66,

Thank you for your message. We can appreciate how confusing this is, especially as the iPhone X was working fine with the iD Mobile SIM only a few weeks ago.

We have not intentionally blocked older iPhones, however this issue can sometimes occur following the UK 3G network switch-off and changes to network carrier settings on older devices. As we operate on the Three network, which has retired its 3G service, some older devices can become stuck in a situation where they recognise the SIM and show 4G, but are unable to connect properly for calls, texts, or data.

Before concluding that the handset is incompatible, please try the following:

1. Check for a Carrier Settings Update

• Connect the iPhone to Wi-Fi.
• Go to Settings > General > About.
• Remain on this screen for around 30 seconds.
• If prompted with "Carrier Settings Update Available", please accept it.

2. Reset Network Settings

• Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.
• This will clear old network settings and force the phone to refresh its connection profile.

3. Toggle VoLTE

• Go to Settings > Mobile Service (or Cellular) > Mobile Data Options > Voice & Data.
• If a VoLTE option is available, switch it off and back on. On some devices this setting may be enabled automatically and not visible.

Given that the iD Mobile SIM works in newer devices and another network's SIM works in the repaired iPhone, this points more towards a device configuration issue rather than a fault with the SIM itself.

Please try the steps above and let us know the outcome. We'll be happy to investigate further if the issue persists.

Thanks.