The Inter-Roaming protocol is a functional protocol for eRoaming platforms to communicate and exchange data between themselves and to expose their data to the Nemo Hyper-Network. The interfaces served by the Inter-Roaming protocol are the exchange of static and dynamic charge point information, authorisation data and charge detail records.The Inter-Roaming concept greatly simplifies the inter-connection between actors (CPOs or eMSPs), regardless of their physical connection. An actor needs simply to connect to one eRoaming platform either directly or indirectly, via another platform or via NeMo, and the actor has access to all actors that are connected either to NeMo directly or to all connected eRoaming platforms. Similarly, an eRoaming platform can connect with all other already connected platforms either directly or via NeMo. The proposed protocol is a functional one, each new eRoaming platform will have to cater for its own technical implementation. The implementation was done for the two eRoaming platforms of the project. Any new eRoaming platform that wishes to join the NeMo Hyper-Network can follow a similar implementation.