WAN and HAN

Smart meters don’t use the internet and have their own closed communications system.
Your electricity smart meter contains a SIM card and uses a signal just like your mobile phone. So if it’s in a place with poor signal it won’t communicate with us.

WAN
Wider Area Network - which connects your meters to OVO. WAN uses the mobile signal to send us your electricity and gas meter readings.

HAN
Home Area Network - which connects the devices in your home. Your electricity smart meter creates a short-range wireless network. This allows it to communicate with your gas smart meter and your In-Home Display (IHD).

Your gas meter doesn’t have a SIM card. It uses HAN to send its messages to your electricity smart meter, which then forwards them to OVO.