[sip-comm-dev] audio/video connection & NAT

Mr Smith mr.smith476 at googlemail.com
Tue Aug 24 18:05:40 CEST 2010

I am testing connection with SIP accounts (iptel & ippi) and SC (latest windows installer
under WinXP on both ends and broadband connection; WLAN and LAN):

Audio quality (with zRTP) is sometimes very good (no jitter, clear sound like skype), but more times very interrupting and sounding like telephone.
I have no idea on what this depends on.

other scenarios:

I am not behind NAT.

Partner A is behind NAT (ADSL router), Partner B not (academic institute):

with Partner A:
The connection is only possible if I am calling, if he calls me then the window tells
"connected *" with an asterisk but no audio connection is establishing.
If I push the "toogle video" button I can see myself in the small preview window but
partner A does not see me.
When he pushes the "toogle video" button, strange and loud sounds appear and the connection
interrupts, so the video connection does not work.

with Partner B:
Audio and Video are working in both directions (with zRTP), Video quality is sometimes pixelig and coming "in waves",
also the motion of the lips and the sound are not synchron (delayed), jittering occurs occasionally as well

I have no experience with wireshark etc - are there any workarounds?

kind regards, MS

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