Panasonic KX-TDA0480, Getting Started

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A1 VoIP Requirements
Getting Started 57
Is the card located appropriately?
Transmission delays can cause pauses and loss in VoIP communications. The more network
devices (e.g., routers and switches) there are between the communicating cards, the larger the
transmission delays, because a certain amount of delay is inevitable when packets go through
each network device (hop).
One preventative measure is to install the card so that the number of transmission hops is kept
to a minimum. In the diagram below, the card is located as close to the IP network interface as
possible.
A1.3 Network Devices
You must evaluate the network devices that are used in the existing network to see if a VoIP
network can be implemented. Below are the points that should be taken into your evaluation.
Can the firewall pass packets from the VoIP Gateway Card?
If the VoIP network contains a firewall, the firewall must be configured appropriately to allow
VoIP packets, which are listed in the table below, to pass through the network without being
blocked by filtering.
For more information, consult your network administrator.
Protocol TCP/UDP Default Port No.
HTTP
*1 TCP 80
RTP/RTCP *2 UDP 5004 to 5011
H.225.0 Call Signaling
*2 TCP 1720
H.245 *2 TCP 1712 to 1724
H.225.0 RAS
*2 UDP 1719
*1 For the actual setting values, refer to "2.2.2 H.323 Parameters" in the VoIP Gateway Card
Programming Guide.
Router
Switch
Too many hops
Switch
Hub
Router
Switch
Better
(PBX located nearest IP network access point)
Switch
Hub