Router Configuration Requirements for VoIP Operation

For VoIP operation, some adjustments to the configuration of the routers in your network may be required. The configurations required are those concerned with setting the priorities for IP voice packet transmissions and ensuring that call setup requests are reachable to the destination nodes.

Here are some points of which you need to be aware when setting router configurations:

• TCP port 1490 is used for VoIP call management.
• UDP port 490 is used for VoIP voice packets. These packets should receive the highest priority with all routers.
• The voice packets (speech bundles) use RFC 1889 RTP encapsulation.

Generally, you will want to establish router priorities as follows:

• Prioritize IP protocol 17 decimal (11 hexadecimal) over any other protocol.
• Prioritize packets to UDP port 490 decimal (1EA hexadecimal).
• Prioritize by IP addresses (the reachable IP addresses for VoIP calls).