When I call phone numbers, both landlines and cell phones, the other person can't hear me even if I can. When calling Skype users with the same hardware and setup, however, everything work fine and the other person can hear me.
I double checked the audio and Skype settings, went through the troubleshooting documentation for similar issues at Skype's site, and checked the support forum. Also, I have enough credit for calling phone numbers.
I use Skype 126.96.36.199 Beta under Fedora 15 with Pulseaudio and a Logitech C300 webcam.
When I make or receive a call from someone in my contacts list, they can not hear me. I have checked my sound setting in my computer. I can hear and see their video very well.