Open InterCharge Protocol (OICP), commonly referred to as OICP, is a communication protocol designed to enable seamless e-roaming between EV charging networks. The protocol allows drivers to access multiple charging networks using a single account while maintaining secure, standardised data exchange between charge point operators and mobility service providers. OICP transmits authentication requests, session data, tariff details, and billing records in a consistent format that supports interoperability and accurate settlement. Standardised communication enables roaming access, simplifies billing relationships, and supports reliable cross-network charging without requiring separate registrations.
What is OICP in EV charging?
Open InterCharge Protocol (OICP) in EV charging is a standardised communication protocol that connects different charging networks so drivers can access charging services beyond their home provider. Roaming capability allows a driver registered with one mobility service to charge at stations operated by another network without creating a new account or payment relationship.
OICP establishes structured data exchange between charge point operators and eMobility service providers for authentication, session control, tariff transmission, and billing settlement in EV charging environments. The protocol transmits driver credential validation, charge point status, pricing information, and session records in a consistent format that supports interoperability across multiple platforms.
Charging networks, mobility service providers, and roaming hubs use OICP to ensure easy cross-network charging access, accurate billing, and reliable charge point discovery. Drivers locate, authenticate, and pay for charging across interoperable networks using one application, radio frequency identification (RFID) credential, or service contract, which simplifies travel and expands usable charging coverage.
Who developed the OICP protocol?
Open InterCharge Protocol (OICP) was developed by Hubject, a Germany-based eMobility interoperability company founded by major automotive manufacturers and energy providers. Hubject created OICP to enable standardised communication, authentication, and settlement between charge point operators and eMobility service providers, forming the technical foundation of the Intercharge roaming network used across Europe and other global markets.
Is OICP an open standard protocol?
Yes. Open InterCharge Protocol (OICP) is an open standard protocol. OICP is publicly documented and maintained to support interoperability between charge point operators and eMobility service providers. The protocol defines standardised data formats and communication procedures for authentication, roaming, session exchange, and settlement across charging networks. Industry participants can implement OICP without proprietary licensing barriers, which enables broad adoption and cross-network compatibility. The protocol is widely used in roaming ecosystems, particularly across Europe, where interoperability requirements and multi-network access drive standardisation.
Why is OICP important for eRoaming networks?
Open InterCharge Protocol (OICP) is important for eRoaming networks because it enables EV drivers to access charging stations outside their home network through standardised communication between charge point operators and mobility service providers. OICP authenticates driver credentials, authorises charging sessions, and exchanges session data for accurate billing and settlement across different providers within eRoaming networks. The protocol distributes location, availability, and tariff information so driver apps can discover accessible chargers and confirm roaming eligibility. Standardised data exchange reduces integration complexity, supports transparent pricing, and allows charging networks to interoperate without proprietary barriers. The roaming framework simplifies authentication, billing, and network discovery while expanding charging access across multiple providers.
How does OICP work in EV roaming?
Open InterCharge Protocol (OICP) works in EV roaming by coordinating authentication, authorisation, and billing between the driver’s home mobility provider and a foreign charging network. A charging session begins when a driver plugs into a charge point operated by a different network, and the charge point operator sends an authorisation request through the EV roaming hub to the driver’s home eMobility service provider. The home provider validates the driver’s contract or token and returns approval, so charging begins. The charging network records session details such as energy delivered, duration, and location, then transmits the data through OICP for billing and settlement between operators. The home provider invoices the driver under the existing service agreement, which allows access to multiple charging networks without separate accounts or payment methods.
How does OICP handle authentication requests?
Open InterCharge Protocol (OICP) handles authentication by transmitting a driver’s identification token from the charging station operator to the driver’s home mobility service provider for validation before a charging session begins. The charge point operator sends an Authorise request that contains the token identifier (RFID UID, app credential, or contract ID) and station details. The mobility service provider verifies the token against its customer database and returns an authorisation response that approves or rejects access. A successful response allows the charging session to start, while a rejection prevents energy delivery. OICP supports secure transmission over encrypted connections and records authentication results for auditing and settlement. The process makes roaming access by confirming driver eligibility across interoperable charging networks in real time.
How does OICP enable charge point discovery?
Open InterCharge Protocol (OICP) enables charge point discovery by distributing standardised location and availability data from charge point operators to eMobility service providers, which allows driver apps and fleet platforms to display accessible charging stations across roaming networks. Data originates from the EV charge point operator (CPO) and includes station identifiers, geographic coordinates, connector types, power levels, operating hours, and access restrictions so mobility platforms can present accurate search results. The protocol provides real-time or near-real-time status updates that show availability, occupancy, and fault conditions, which help drivers select operational chargers. Tariff data and roaming access indicators allow platforms to confirm whether a driver’s contract is valid at a specific site. The structured data exchange ensures consistent charge point visibility and reliable discovery across interoperable charging networks.
What data does OICP exchange between networks?
Open InterCharge Protocol (OICP) exchanges operational, authentication, and financial data between charge point operators and eMobility service providers to enable roaming access and accurate settlement. OICP sends authentication requests from the charging station and associated electric vehicle supply equipment (EVSE) to the driver’s home network and confirms charging authorisation through secure token exchange before a session begins. The protocol transmits session start and stop records, energy consumption data, timestamps, location identifiers, and charging duration to support billing and clearing. OICP communicates tariff information, pricing elements, and currency details to ensure cost transparency and settlement accuracy. Status updates, charge point availability, and fault notifications allow networks to maintain operational awareness. Secure transmission and standardised data structures ensure reliable interoperability and trusted roaming transactions across connected charging networks.
What are the main OICP message types?
Open InterCharge Protocol (OICP) defines standardised message types that enable roaming authentication, session control, and billing data exchange between charge point operators and eMobility service providers. Core message types include Authorise, which validates driver credentials before charging begins. StartSession, which initiates a charging transaction after successful authentication; and StopSession, which ends the transaction and records energy usage for billing and settlement. StatusNotification messages communicate charge point availability, faults, or operational state changes in real time. TariffInformation messages provide pricing details used for cost transparency and settlement accuracy. The message types ensure consistent communication, reliable roaming access, and accurate financial reconciliation across interoperable charging networks.
How is OICP different from OCPI?
Open InterCharge Protocol (OICP) differs from Open Charge Point Interface (OCPI) in primary purpose and operational scope. OICP functions primarily as a roaming protocol that connects charge point operators and eMobility service providers through centralised hubs to enable cross-network authentication, session exchange, and settlement. OCPI focuses on direct operational communication between platforms, supporting real-time charge point status updates, session control, tariff transparency, and energy transaction management. OICP enables drivers to access multiple charging networks through roaming agreements, while OCPI enables operators and service providers to exchange live operational data and pricing information. The two protocols support interoperability, but OICP emphasises roaming connectivity and commercial clearing, whereas Open Charge Point Interface (OCPI) emphasises operational control and real-time integration.
Can OICP work with OCPI systems?
Yes. Open InterCharge Protocol (OICP) can work with OCPI-based systems through interoperability layers, middleware, or platform gateways that translate data between the two protocols. OICP is primarily designed for roaming and settlement between charge point operators and eMobility service providers, while OCPI focuses on real-time operational integration, tariff transparency, and charge point status exchange. Integration platforms or roaming hubs can map authentication data, session records, pricing information, and billing transactions between OICP and OCPI environments. The translation enables networks that use OCPI internally to participate in OICP roaming ecosystems without replacing existing infrastructure. Operators deploy dual-protocol support or use interoperability platforms to connect OCPI-managed networks with OICP roaming hubs, which allows drivers to access broader charging coverage while operators maintain their preferred operational systems.
When should operators choose OICP over OCPI?
Operators should choose Open InterCharge Protocol (OICP) when the primary objective is cross-network roaming that allows drivers to authenticate, access, and pay for charging across multiple networks through a single mobility provider. OICP is optimised for roaming relationships between charge point operators and eMobility service providers, with standardised data exchange for authentication, session records, and settlement across large roaming ecosystems. OCPI (Open Charge Point Interface) is better suited for real-time operational integration, dynamic pricing management, and direct system-to-system communication between platforms that require live tariff updates, charge point status control, and energy transaction management. OICP supports broad roaming coverage and commercial clearing, while OCPI supports operational control, transparency, and real-time pricing functions, so protocol selection depends on whether roaming access or operational integration is the primary requirement.
Which platforms use OICP?
The platforms that use OICP are listed below.
- Hubject Intercharge network: Hubject operates one of the largest global EV roaming platforms, and OICP serves as the core communication protocol that enables authentication, session data exchange, and cross-network billing. The Intercharge ecosystem connects hundreds of charging networks and mobility providers worldwide.
- Gireve roaming platform: Gireve provides a Europe-focused interoperability platform that enables roaming between charging networks and service providers. OICP enables standardised data exchange, tariff transparency, and transaction settlement across participating operators.
- European eRoaming networks: Major roaming ecosystems across Europe rely on OICP to enable cross-border charging access. Networks operating in Germany, the Netherlands, France, and the Nordic region use OICP to support seamless driver authentication and billing across multiple providers.
- Charge point operators and mobility service providers: Many charging networks and mobility platforms integrate OICP to support roaming and interoperability. Operators in Germany, the Netherlands, and broader European markets rely on OICP to connect infrastructure, expand coverage, and allow drivers to access multiple networks using one contract or application.
How does OICP improve EV charging interoperability?
Open InterCharge Protocol (OICP) improves EV charging interoperability by enabling standardised communication and data exchange between charge point operators (CPOs) and eMobility service providers (eMSPs), which allows drivers to access multiple charging networks through a single account. OICP supports roaming by transmitting authentication credentials, tariff data, session records, and billing information in a consistent format across different platforms. The protocol enables real-time charge point availability updates, remote session control, and automated settlement processes, which ensure smooth charging access regardless of network ownership. Standardised interfaces reduce system integration complexity, support cross-network compatibility, and allow charging infrastructure providers to expand coverage without proprietary barriers. The standardised roaming framework enables EV drivers to locate, access, and pay for charging services across interoperable networks using one application, RFID credential, or contract.
How secure is OICP communication?
Open InterCharge Protocol (OICP) communication is highly secure because it uses encrypted data transmission, authenticated network connections, and controlled access procedures to protect charging session data and roaming transactions between charging networks. OICP operates over HTTPS with Transport Layer Security (TLS), which encrypts data exchanged between eMobility service providers and charge point operators to prevent interception or tampering. Certificate-based authentication and API credential management verify system identities and restrict unauthorised access. Message validation, transaction logging, and audit trails support fraud detection and operational accountability. Network operators deploy firewalls, secure gateways, and monitoring systems to protect backend infrastructure from intrusion attempts. Security effectiveness depends on proper implementation, certificate management, and regular updates, but OICP is designed to meet commercial roaming requirements for reliability, data integrity, and secure interoperability.