Polycom 4300T Benutzerhandbuch

User Guide V

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IU 4300T Converged Network Appliance

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A typical 4300T installation for an IP Centrex application requires no external 

router or firewall.  The 4300T WAN port is connected directly to the T1/E1 line 

and the LAN port(s) are connected directly to enterprise devices and/or 

Ethernet switches. 

VoIP signaling is performed in the service provider network via a softswitch 

and the 4300T acts as a proxy for the voice devices installed in the enterprise 

LAN.  In this configuration a single public IP address is used to proxy for all 

of the IP phones and to route to multiple PC’s installed on the LAN. 
The 4300T performs the following functions in this application:

• WAN/LAN IP routing.

• Traffic shaping and priority queuing to guarantee high quality voice 

traffic.  These mechanisms protect voice and data traffic from contending 

for the same network resources to guarantee low latency and the highest 

call quality possible for VoIP traffic.  At the same time they ensure the best 

utilization of WAN bandwidth by enabling data traffic to burst up to full 

line rate in the absence of voice calls.  Precedence is automatically given to 

traffic coming from IP phones and other devices using the 4300T’s 

Application Layer Gateway function.  

Application Server

Softswitch

Gateway

Gateway

PSTN

PSTN

NMS

EM003