The smallest of the Ingate SIParators, the Ingate SIParator® 21 is designed for local and small offices. The Ingate SIParator® 21 is an add-on to existing firewalls that seamlessly enables the transmission of realtime communications without affecting firewall security. The SIParator® 21 handles the SIP signaling and media streams, routing them to and from the private IP addresses of authorized users on the LAN. As needs increase, the SIParator® is easily scalable for additional users; with the purchase of software license upgrades, the Ingate SIParator® 19 can support up to 40 simultaneous sessions in a VoIP application. As with all Ingate SIParators and Firewalls, the SIParator® 19 has everything necessary for SIP traversal, including a SIP registrar and a SIP proxy, support for NAT and PAT and support for TLS and SRTP for encrypted signaling and media.