No doubt that Romanians love open source. It was proven before with Linux and PHP and now it will be demonstrated again with VoIP/SIP. At least 2 open source VoIP projects were started and heavily developed in Romania:
OpenSER. An open source PBX derived from SIP Express Router. In June 2005, two SER core developers Bogdan-Andrei Iancu, Daniel-Constantin Mierla and one main contributor Elena-Ramona Modroiu (all Romanians) started OpenSER project. Many others joined later.
Yate. An open source IP-PBX developed in C++. For quite some time it was solely developed by Paul Chitescu and Diana Cionoiu, Romanian programmers.
Besides these projects, Asterisk has a solid user base in Romania.