SIP enabled firewalls are standard firewalls with additional SIP protocol support. This additional support provides the protocol intelligence needed to enable SIP and its related protocols to pass through a network address translating (NAT) gateway. In addition to these functions, most SIP enabled firewalls provide protocol checking and include defenses against flooding attacks and some classes of Denial-of-Service attacks. In general, SIP enabled firewalls lack facilities to provide true application level security. A SIP enabled firewall will not provide spam controls, content controls or advanced policy controls. Where SIP enabled firewalls score is in their ability to provide good network level protection. Most SIP enabled firewalls are mature products that have benefited from many years of deployment experience.
Product examples include Checkpoint, Juniper and Cisco.