Since a couple of weeks I started facing a problem when calling to "non skype users", i.e. fixed or mobile's lines. I can hear the other person very well, but they cannot hear me, and after 10 seconds (aprox) the communication is cut off automatically.
I tried all the options in my Audio Settings (internal and external micro, with/without auto adjust, etc), the sound level shows normal, I upgraded to latest version (18.104.22.168, I put all the PC audio settings to their max, even if I call the Skype Test I can hear my voice and my recording very well.... But still other people cannot hear me.
I have a HP Pavillion dv6 with integrated micro, and Windows 7 - 64 bits
It sounds like you've done all you can do at your end. I suggest you contact Skype Customer Service to see if there's a problem with the PSTN (telephone) service in the area you're calling, and if they can correct it. Start with this link: