Are the network devices located appropriately for effective VoIP
communications?
Transmission delays can cause pauses and loss in VoIP communications. The more network devices (e.g.,
routers and switching hubs) there are between the PBX and IP telephones or the IP network interface, the
longer the transmission delays. This is because a certain amount of delay is inevitable when packets go through
each network device.
To prevent unnecessary delays, it is recommended to connect the PBX as close to the IP telephones and the
IP network interface as possible so that the number of the network devices is kept to a minimum.
IP Network
RouterRouter
Switching
Hub
Switching
Hub
Switching
Hub
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 appropriately?
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.
[IP Packets from MPR/IP-EXT16 Card and IP Telephones]
Protocol
Description TCP/UDP Default Port No.
RTP (IP telephone
connected to MPR)
Real-time Transport Protocol.
Used for voice data transmission.
UDP 12000 to 12255
RTP (IP-PT connected to
IP-EXT16)
UDP 8000 to 8063
Maintenance (MPR) Panasonic proprietary protocol.
Used for communication parameter
negotiation with the PBX, download of
country/area data, confirmation of
connection with the PBX, and
notification of error messages and
statistical information to the PBX.
TCP 35300
Maintenance (IP-EXT16) UDP 9300
Maintenance (IP
telephone)
UDP 9301
MGCP (MPR/IP-EXT16) Media Gateway Control Protocol.
Used for call control command data and
LCD/LED data transmission.
UDP 2727
MGCP (IP telephone) UDP 2427
20 IP Networking Guide Document Version 2010-08
2.1.3 Network Devices
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