» cFosSpeed 문서, 탁월한 Voice-over-IP (VoIP) 음성 품질

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탁월한 Voice-over-IP (VoIP) 음성 품질

Not only is minimal latency absolutely essential for Voice-over-IP, it is the single most important factor in improving speech quality.

Traffic Shaping 기술은 짧은 핑시간과 안정된 빠른 전송속도를 동시에 유지합니다.

RTP detection integrated in cFos and cFosSpeed permits prioritizing VoIP and other live streams (like conference channels).

Deactivation of strict RTP verification

Its prioritization can be adjusted under Protocol or Program Settings. Should a particular live stream not be recognized, you can prioritize the respective program by name.

Please note that some programs (like VoIPBuster, IxChariot) only use RTP but not the corresponding RTCP connection. For these, you should deactivate strict RTP verification in the settings.

Dropouts During Download:

VoIP connections usually suffer from dropouts when downloads are simultaneously run at full speed. Thanks to their integrated RX shaping, cFos and cFosSpeed help avoid this problem by keeping ping times consistently low.

Program prioritization of Skype


Skype employs a proprietary encrypted protocol that cannot be detected by a Layer-7 analysis without considerable effort. To allow users to prioritize Skype nevertheless, we have entered it in our program list.

VoIP via Router Prioritization:

Some routers (like the Fritz!Box) are equipped with phone jacks. If a jack is used, all VoIP data will be transmitted directly to the Internet bypassing cFosSpeed entirely. Such routers may restrict the available bandwidth when a VoIP call is made causing a negative impact on Traffic Shaping performance. Therefore we recommend making VoIP calls from your computer, not the router, to allow cFosSpeed to detect and prioritize them.

연결설정 최적화:

DSL 연결 설정

연결설정에서는 전달매체를 정확하게 지정할 수 있습니다. cFos 나 cFosSpeed에 연결에 관한 보다 많은 정보가 가능할 수록, 보다나은 핑시간을 얻을 수 있습니다. 디폴트 값은 "Adaptive"입니다. 예를 들어, 만약 DSL연결을 사용하고 있다면, 적절한 DSL기준이나 프로토콜을 당신의 매체로 선택해야 합니다.

선호 핑:

선호 핑 보기

부가적으로 환경매뉴의 설정을 사용할 수도 있고 상태윈도우의 "Favor Ping"을 기동시킬 수도 있습니다. 그러면 초록색 화살표가 상태창에 나타납니다. 이 설정은 cFos 나 cFosSpeed가 핑 타임을 최고화하기 위하여 모든 노력을 다한다는 것이나. 이에 따라 전송속도가 현저하게 느려지기도 합니다.

VoIP Software in use with cFosSpeed


Measurements with IxChariot

We tested our software using IxChariot (a network performance testing tool provided by Ixia) to evaluate the benefits of cFosSpeed Traffic Shaping. For this purpose we monitored the VoIP parameters with IxChariot while performing multiple uploads.

You can easily notice that without cFosSpeed normal VoIP communication is not possible during an upload, but it proceeds almost unaffected when using cFosSpeed.

MOS value

In particular, you can see the MOS value ( http://en.wikipedia.org/wiki/Mean_opinion_score ) decreasing rapidly towards 1 after starting the upload. This means that the connection has become unusable for voice transfer. When using cFosSpeed the value doesn't decrease - the speech transmission retains its high quality.


The delay is a crucial part of the MOS value. Using cFosSpeed keeps the increase of this delay within bounds, whereas it raises up to 700 milliseconds when not using cFosSpeed (red graph).

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