you can find the decree law translation on ictQatar, google this.

and you will be able to find the law on their website, however the law does not state that the news paper states, which is to use a cheaper method of calling, it states only that selling a telecommunication service without a license is a breach and so the fines would occur.
so you should be fine.

Like everyone says, they have the ability to block the voip ports along with the websites that provide the software to use the technology but they don't so really its their own fault if they are loosing business.