A roaming firewall is a roaming gateway connecting the Evolved Packet Core (EPC) of the home network to the EPC of the visited network to handle roaming handover.
With a roaming firewall, networks are protected through a combination of security capabilities, including:
Encryption of GTP-C and GTP-U traffic with IPsec
Rate limiting of GTP-C traffic
Prevention of GTP-C-specific attacks
Signaling normalization and modification of GTP-C traffic, including 3GPP release interoperability