We're sorry for the inconvenience and it's nothing to be too concerned about.
A simple settings change will restore your service.
To prevent this happening again, visit https://www.plan.com/apn-settings and reconfigure your phone's data settings, for your operating system.
To ensure the best possible performance, even if it appears your data settings are correct on-screen, please reconfigure them as per the guide.
Once we detect your data settings have been reset correctly, Wifi / 4G calling will be restored.