There is provided an apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive, at a first network repository function in a first network from a security edge protection proxy in a second network, a request for discovering one or more roaming hubs and/or security edge protection proxies in the first network; and send, from the first network repository function to the security edge protection proxy in the second network, a response comprising information identifying the one or more roaming hubs and/or security edge protection proxies in the first network and information identifying one or more further networks which can be reached via a respective roaming hub and/or security edge protection proxy in the first network.