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The Media System Configuration contains system-wide settings for the Media System, configuring the media system means setting the number of RTP/RTCP port pairs and the starting port. Other aspects of media handling, such as Media Profiles, Lists, and Media Crypto Profiles are handled in different sections of the UI and are explained on their own topic pages.

UDP ports are used for transmission of VoIP calls employing RTP protocols (RTP over UDP). The start port is the first port that can be used for a call. Calls require a pair of ports, one for the voice the other for the control information (RTP/RTCP). The number of port pairs determines the number of simultaneous IP Call Legs on the UX. For example; if you have 100 pairs, you can have a maximum of 100 simultaneous IP Call Legs. This does not affect the number of TDM/TDM calls.


If you have 100 pairs, and every call has one IP call leg, and one TDM call leg, then you can have 100 calls. However, if a call is IP on the inbound, and also IP on the outbound leg, then it requires two port pairs and this reduces the total number of simultaneous call accordingly (i.e., maximum of 50 IP/IP calls vs. Max 100 IP/TDM calls).

Configuring the Media System

  1. In the WebUI, click the Settings tab.
  2. In the left navigation pane. go to Media > Media System Configuration.

Media System Configuration - Field Definitions

Start Port

Specifies the starting number for the RTP and RTCP port range.

To determine the last port number:

First Port Number + (2*Number of Port pairs) - 1.

Given: default value for starting port number (16384) and the (default) number for port pairs is 600.
There are 600 pairs, meaning there are 1200 individual ports. 16384 + (1200-1) = 17583

Number of Port Pairs

The number of RTP and RTCP port pairs used by the UX system. For example, if the default values are used for starting port number and number of ports, the last port number would be 10959.

Echo Cancel NLP Option

Specifies the level of echo cancellation employed by the UX Nonlinear Signal Processor.

The default value is Mild. However there are two additional levels of echo cancellation, Strong and Aggressive. As each telephony system implementation varies, their echo characteristics similarly vary. Adjust the level of echo cancellation to suit your particular deployment. Too little cancellation may result in a persistent echo, too aggressive and you may experience voice "clipping".