Roaming

Charging in another company's network with your own card or app.

Explained in

EV charging fundamentals · Stop 03What happens after you tap your card?Follow one tap from the card reader to the operator's backend and, for another company's card, across the roaming route and back. OCPP and OCPI in action.

A simple way to keep them apart: OCPP stays with the charge point, OCPI works between companies. OCPI is not the only roaming protocol. The Hubject platform, for example, uses its own protocol, OICP.

From “Two protocols with two jobs”, stop 03

Also in

  1. EV charging fundamentals · Stop 01Why does charging feel more complicated than refuelling?A familiar pattern
  2. Charging infrastructure · Stop 03Which permits and contracts does a site need?Contracts the driver never sees
  3. OCPP in depth · Stop 09One day of messages, fully understoodWhere to go from here
  4. OCPI and roaming · Stop 01Why does a card work at someone else's charger?Two roles, one session
  5. Plug & Charge · Stop 08One plug-in, fully understoodWhere to go from here
  6. Payments and billing · Stop 01How is a charging price built?Rules for the price itself
  7. Business models · Stop 02How does a CPO earn money?Rules for the operator's price
  8. Fleet charging · Stop 06How are charging costs tracked across a fleet?One view per vehicle

Named in 12 further stops as well.

  1. OCPPOpen Charge Point Protocol: the open protocol between a charger and its operator's backend.
  2. OCPIOpen Charge Point Interface: an open protocol for roaming between operators and e-mobility service providers.
  3. OICPOpen InterCharge Protocol: the roaming protocol of the Hubject platform.
  4. Roaming hubA platform that connects many operators and service providers, each through one connection.
  1. Hubject: Open InterCharge Protocol (OICP), specification on GitHub. https://github.com/hubject/oicp. Checked 07 Oct 2026.