From O'Reilly Skype Hacks: "If either end of a Skype call has poor UDP, call quality will suffer"
I use the SOCKS5 proxy /w authentication for Skype, and have no problems making/receiving calls.
I have an allow all firewall rule for the port I'm using for incoming connections.
and a DNAT rule: Allow - Any->Skype->WAN - Dest: MYPC - Auto Firewall rule
I tried turning off IPS or making an allow all for ICMP/UDP in IPS exceptions as a test - no good
Also tried turning of ICMP and UDP flood protection.
All tests with the Skype Echo Call Test Service consistently show bad local UDP,
in the Call Technical Info dialog.
As I understand it, the new version of the Skype app is supposed to work without explicitly setting it to use the proxy explicitly. I have not confirmed that with any test myself.
Cheers - Bob
Sophos UTM Community Moderator Sophos Certified Architect - UTM Sophos Certified Engineer - XG Gold Solution Partner since 2005