Polycom 4300T Benutzerhandbuch

User Guide V

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IU 4300T Converged Network Appliance

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We strongly recommend that you change the default password for the root 

administrative account using the following steps:

Enter the password you chose in step C again in the Confirm Password to 

ensure that there were no mistakes in the initial entry.

Press Submit.

The 4300T provides a VoIP application layer gateway (ALG) for the SIP, 

MGCP, and H.323 protocols. The ALG proxies the connection between the 

VoIP softswitch, IP PBX or gatekeeper and voice and video devices such as IP 

phones, IADs or softphones.  By acting as a proxy the 4300T is able to provide 

several important functions for IP based voice and video:

• Provide NAT/PAT services for voice and video traffic. NAT/PAT for 

VoIP enables you to use a single public IP address on the WAN interface 

of the 4300T to represent multiple private IP addresses assigned to voice 

or video devices on the LAN.  The NAT function maps both IP address 

and IP port number between the public and private addresses so that all 

signaling and VoIP media packets are translated.  A single public IP 

address can support up to 253 voice and video devices.

• Provide security services for voice and video traffic. 

— NAT/PAT services hide enterprise LAN topology from hackers. 
— The ALG acts as a “voice and video aware” firewall and ensures only 

authenticated voice traffic enters the enterprise LAN.  This is 

accomplished by the dynamic provisioning of signaling and media 

ports for authenticated voice devices.  The implementation is stateful 

and open ports are closed automatically when no longer required to 

support the voice or video call.

The new password must be between 6 and 20 characters in length.  Any 
combination of alpha and numeric characters is accepted.