Panasonic KX-TDA50, Manual, Page: 15 / 48

2.1 VoIP Requirements
Information about IP Proprietary Telephones 15
Are the IP-EXT card and IP-PTs located appropriately?
Transmission delays can cause pauses and loss in VoIP communications. The more routers there are
between the IP-EXT card and IP-PTs, the longer the transmission delays. This is because a certain amount
of delay is inevitable when packets pass through each router.
Additionally, the more switching hubs between the card and IP-PTs, the longer the transmission delays,
because the switching hubs must also handle the network traffic generated by other terminal devices (e.g.,
PCs) connected to them.
To prevent unnecessary delays, it is recommended to connect the card and IP-PTs so that there are as few
network devices (e.g., routers, switching hubs) between them as possible.
2.1.3 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 evaluated.
Can the firewall pass packets from IP-PTs?
If the VoIP network contains a firewall, the firewall must be configured appropriately to allow VoIP packets,
listed in the table below, to pass through the network without being blocked by filtering.
For more information, consult your network administrator.
Protocol Description TCP/UDP Default Port No.
RTP (IP-EXT) Real-time Transport Protocol.
Used for voice data transmission. UDP 8000 to 8063
(IP-EXT16)
8000 to 8015
(IP-EXT4)
RTP (IP-PT) UDP 8000 to 8063
(IP-EXT16)
8000 to 8015
(IP-EXT4)
IP Network
Router Router
Switching
Hub
Switching
Hub
Switching
Hub