Skype, Yahoo, msn etc. are not illegal for personal use in Qatar and if it was illegal they could have easily blocked them. I saw recently an interview with the Skype Official in one of the magazines here in which he states that they are in the process of opening their Office in the Middle East. It is illegal to use those voip services for business to make money as most of such users were cracked and caught by the Authorities but still there are some working in the inner areas where checking is rare.