#Best codec for fax over voip how to

If I dont put G722 on top of the list it never will be used if I start the call. Only calls to customers which also use QSC will be done using G722. I think, if I want to use G722 the preference should look like this:īut if I do this, and make an outgoing call, QSC will most of the time force G711, so the pbx has to transcode. There are 3 places where this can be done: Now, to use G722 I have to put it on top of the list of preferred codecs.

#Best codec for fax over voip how to

So, it is doable.Īnother thing is how to use G722 without transcoding? The provider I use (QSC) supports G722.

Then we know that for sure.Īlso, the pbx from starface seems to have no such problems. Thats right VoIP phone systems allow you to place cloud calls on a phone, computer, or mobile device. Analog phone With an Analog Telephone Adapter, you can convert your regular phones analog signal into a digital format that can be transferred over the internet. I guess a current version of ffmpeg will deliver perfect quality. With smartphones, VoIP calling is as easy as downloading an app. But regarding the frequency range this should not be a real problem because you can limit the frequency range to what G711 allows, and apply a digital filter with noise or silence. I partly agree with you the other way around, if you transcode G711 to G722 - which will happen with the data the called party sends, then you have to interpolate data. Its like reducing the size of a jpeg which normally can be done without quality loss.

Transcoding from G722 to G711 should be possible without loss of quality compared to using G711 in the first place. G722 is a wideband codec, and G711 carries less information compared to G722:

711 as the transport method for FoIP is an extension of traditional PSTN audio-based faxing. It uses an uncompressed format and requires high bandwidth, typically about 64 kbps. But still I think there is a problem in the used decoder/encoder. 711 is an ITU-T recommendation for Pulse Code Modulation (PCM) of voice frequencies.