VoIP is one of the fastest growing businesses in Iran 'cause of expensive international communication services provided by telecom company.
The open source community has been very active on this subject that could attract major IP telephony providers like Cisco and Dialpad to its work, One of the most successful communities in this area is Vovida,If you are planning to develop a VoIP services network I strongly recommend you to go through Vovida's web site, they've also very nice presentations on VoIP systems which are very good for beginners and Managers who want to get familiar with VoIP.