Recertification Fee, Transit Server
LifeSize Transit addresses firewall and NAT traversal for SIP and H.323 calls using a client/server approach. LifeSize Transit Server, which resides in the DMZ on your network, is a unified set of firewall
and NAT traversal technologies. It enables firewall and NAT traversal, session and media control for UDP,
TCP, and HTTP media, as well as H.460 control. It also serves as an H.323 gatekeeper or SIP proxy and
registrar. The LifeSize Transit Server is both an H.460 traversal server and a SIP traversal server.
LifeSize Transit Server includes a signaling server that handles firewall and NAT traversal, call setup,
operation and maintenance services and a media server that is optimized for relaying the actual voice,
video, and presentation data. When you install LifeSize Transit Server, you configure each of these
servers with its own static, public IP address (either NATed or un-NATed). Refer to Deploying LifeSize Transit Server with NAT. The public IP address of the signaling server is used by callers outside
your network to place calls to your video communications devices.
LifeSize video communications systems residing behind the firewall in your private network include client
software through which these devices register with LifeSize Transit Server. If your LAN includes a
supported H.323 gatekeeper, an MCU, or supported third party video communications devices, LifeSize
recommends you use LifeSize Transit Client—a standalone multi-user traversal client —to serve as a SIP
and H.323 proxy for calls with LifeSize Transit Server.
The registration to LifeSize Transit Server, either from LifeSize video communications systems or from the LifeSize Transit Client, creates a connection to the server that is kept alive through small packets that are sent at measured intervals, enabling the server to communicate with the client when it receives an incoming call. The client can then initiate outbound connections on the firewall.
