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tscott1614575 asked ·

Exporting/Decoding Call Audio With Wireshark

I'm trying to use Wireshark to diagnose VoIP quality. I can see the SIP calls just fine but cannot get it to play back the call audio. Does anyone know if it's possible to play the audio from a RingCentral call? It appears to be using the Opus codec and I see no indication that the calls are encrypted but maybe I'm overlooking something.
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Chris Rosa avatar image
Chris Rosa answered ·
Id expect the call to be encrypted. I dont know for sure tho. I did find this KB article that seems to support that. https://success.ringcentral.com/articles/RC_Knowledge_Article/7987
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" If you want to enable Secure Voice for your account, contact RingCentral Support." This seems to imply encryption is opt-in, but I'm not sure.
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lee2 avatar image
lee2 answered ·
I have used Wireshark for the same purpose. Once you save the capture and open it, go to telephony on the menu bar and select VOIP calls. You should see the calls from the capture populate there. Then you can select one and Play Streams. You should be able to hear them. I can on mine. 
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I can see the VoIP calls listed here, including the to/from users and phone numbers, but when I try to Play Streams it just doesn't do anything at all, as if there is no data. If I go to Telephony > RTP > RTP Streams, click Analyze and then Play Stream it says "rtp stream is empty or codec is unsupported".
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brett-janzen avatar image
brett-janzen answered ·
Does anyone know if there is a way to get the cert to be able to decode the streams?

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If the streams are encrypted, I would assume they are encrypted by RingCentral in which case you wouldn't be able to obtain that certificate. I've read of people successfully decoding with Wireshark like @lee, above, but have yet to get it to work, myself.
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tscott1614575 avatar image
tscott1614575 answered ·
Actually, I just now found some relevant info and was able to decode audio in Wireshark. According to RingCentral if HD Voice is enabled on the phone it will encode audio with the OPUS codec. If HD Voice is turned off, it will encode with G.722 codec. G.722 can be natively decoded in Wireshark! Check your RingCentral account settings online and go to Phones & Numbers > Phones > Edit (next to the phone in question) and uncheck " Use HD Voice if possible".
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brett-janzen answered ·
I just verified this, the check box for HD calling is NOT checked. I was unable to view the call in wireshark. Do I need to disable encryption or something for this to work?

thanks,
Brett
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tscott1614575 avatar image
tscott1614575 answered ·
In Wireshark, try Telephony > RTP > RTP Streams. Click on one of the found streams and click Analyze. Once the analysis is complete, click Play Streams.

Note that a single phone call will have two streams; one incoming and one outgoing. You will need to highlight both streams before clicking Analyze if you want to play back both sides of the conversation. The only way I know to find the pair of streams is to look at the source and destination addresses and find the two that are similar in size (based on packet count).
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This is the problem, when looking for RTP streams there are none. I found the UDP packets from the phone and did decode as but still wasnt playing correctly, it did see it as g711u.
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G711u is what mine shows, as well. Does it give you any sort of error such as "stream is empty" or "codec not supported"? I suppose it's possible you don't have the needed codec installed for playback. You could try K-Lite Codec Pack.
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