Real-Time Transport Protocol (RTP) Ports

You can configure RTP ports for your environment in the following ways:
  • Filter incoming packets by IP address or port.
  • Reject packets arriving from a non-negotiated IP address, an unauthorized source, or non-negotiated port for greater security.
  • Enforce symmetric port operation for RTP packets. When the source port is not set to the negotiated remote sink port, arriving packets are rejected.
  • Fix the phone's destination transport port to a specified value regardless of the negotiated port.

    This is useful for communicating through firewalls. When you use a fixed transport port, all RTP traffic is sent to and arrives on that specified port. Incoming packets are sorted by the source IP address and port, which allows multiple RTP streams to be multiplexed.

  • Specify the phone's RTP port range.

    Since the phone supports conferencing and multiple RTP streams, the phone can use several ports concurrently. Consistent with RFC 1889, 3550, and 3551, the next-highest odd-numbered port is used to send and receive RTP.