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Xymphony_Programming_-_VoIP_Media_Settings

Some parameters for VoIP codecs and media (like transmit and receive frame lengths, QoS, media jitter buffer) are adjustable in Telesis systems. These parameters are common for both SIP and H.323 VoIP calls.

The parameters can be programmed with using the Media link in Homepage Ethernet paragraph.

The Media link opens Voip media settings page.

Telesis systems have integrated media proxies. This integrated media proxy:

  • receives RTP packets from the originating side,
  • decodes (i.e., converts) received RTP packets to PCM linear codes,
  • switches linear codes within the integrated PCM switch,
  • encodes linear codes according to the requirement of the destination, and
  • transmits RTP packets to the destination.

Telesis systems support for SIP and H.323. Both protocols coexist on the same Telesis system. SIP and H.323 calls may originate and terminate in the same system. Calls between non-similar VoIP entities (like between H.323 and SIP) always use this integrated media proxy.

However, if desired, media proxying can also be applied to the calls between similar VoIP entities (like SIP to SIP or H.323 to H.323) with setting the Media proxy type accordingly in Voip media settings page. Options are:

  • Never: Telesis system always does the media transport direct for the calls of similar VoIP entities.
  • Inside-Outside: Telesis system does the media transport direct for the calls of similar VoIP entities residing in the inside (private) IP address span. However, if one VoIP entity is in the inside and the other entity is in outside (public) IP address span, then Telesis system does the media transport through the integrated media proxy.
  • Always: Telesis system always does the media transport through the integrated media proxy for the calls of similar VoIP entities.

It is recommended to leave Media proxy type as the default one (Never) unless you really know what you are doing. Be aware that; just like VoIP to TDM calls, media proxied VoIP calls also require IP-to-TDM license for both VoIP parties (i.e., for a single proxied IP-to-IP call, one w.pxf.voip002 license is needed). Consequently, unnecessarily setting Media proxy type to Inside-Outside or Always will require more number licenses than the actually needed number.

For G.711, G.723, and G.729 codecs, various transmit and receive parameters are adjustable in Voip media settings page. Help link in each row provides further information when it is clicked on.

ToS (Type of Service) and Differentiated services is a quality of service (Qos) protocol that prioritizes IP voice (RTP payload) and data traffic to help preserve voice quality even when network traffic is heavy. If Qos value of network devices is written in RTP ToS-Diffservices textbox, the system transmits this differentiated services value inside the RTP Payload messages. Consult your network administrator to learn if this protocol is supported by your network. If so, which value is to be used. For most networks Hex B8 is the proper value.

Telesis systems are equipped with an internal jitter buffer to correct transmission jitter in RTP media packets. The length of this Media jitter buffer is adjustable. By default, it is 100 milliseconds. Decreasing this value reduces reception delay but depending the load of the network, reception may be discontinuous. Leave this at the default value unless you really know what you are doing.

When OK button is clicked on, the parameters are stored into volatile memories but they are not activated. In order to activate the modified parameters, these should to stored into nonvolatile memories and then the system should be restarted again. To do this, first operate Save command in Homepage System paragraph, and then operate Reboot command in Homepage Control Program paragraph.

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Page last modified on June 18, 2010, at 08:29 AM EST
Subject to change without any notice. All rights reserved 2010 - Telesis A.S.
Iskitler Cad. No.68 Ankara, TURKEY. Tel: +90 312 3840540 Fax: +90 312 3840549 http://www.telesis-pbx.com