Skype no audio with allow rule

[esampathj]

Dear Team,

Recently we have experianced a skype no audio issue with the latest skype version. We have allowed skype and skype-probe to a test PC and still we have no audio. But when I do a any application allow then we get clear audio. However, with a old skype (version 7.7) audio is working. (latest version 7.37 ) audio is not working. Could you please someone help me to understand what are the application I have to allow to get audio with the latest skype version.

Model PA-500
Application version 661-3842 (02/09/17)
Threat Version 661-3842 (02/09/17)
Antivirus Version
2147-2634 (02/07/17)

Tested Skype version 7.31.0.104 - no audio

Tested Skype version 7.7 - Can hear clear audio

OS version - Windows 7

[BPry]

Are you allowing RTP?

[esampathj]

No I have not specifically allowed rtp. By the way I can see some rtp-base and  rtcp packetes are dropping on the monitoring panel. Please advice. 

[TranceforLife]

Are they from the same source/destination as your Skype session? If yes try to allow and app as pet @BPry advice 

[BPry]

I'm guessing that you are not decrypting traffic correct? Skype is a pretty weird litle cookie; one thing to make sure in addition to everything else is that you are actually allowing the applications Skype depends on. Currently that would be office365-consumer-access, ssl, stun, web-browsing, websocket

[esampathj]

Thank you for the comments. I recently noticed that rtp-base getting blocked by the firewall. Once  enable it call could hear for 20 seconds and teared down. There after inoticed rtcp protocol getting blocked. Is there any specific protocol set I have to allow to skype work correctly.

[BPry]

Really depends on who you are connecting to. In a Skype for Business enviroment it will utilize RTP and RTCP. I've listed a link below that may help you determine what actually needs to be opened. The consumer version of Skype will utilize by default all destination ports above 1024, if it can not access those ports then it 'should' fall back to 80 and 443, in practice however that doesn't always work correctly. 

[DavidMicallef]

Hi

Any news on this one? 

Regards

DM

[BPry]

@DavidMicallef,

If you open a new discussion and give us some details about how your allow rule looks we can probably help you get it working, Skype problems are usually simply access issues. It would be good to include also what you are actually running (Skype, Skype for Business, hosted/on-site)?