I had to write something after reading an article on Australian IT. It is not only that Open Source has traction in VoIP IP Telephony, most of the VoIP was Open Source until recently where big companies were /are still selling legacy telephony switches. Now that companies like Microsoft has entered the arena, there will be analysts who will try to pull wool over eyes of people. What pushed me to even mention this article is the mention of YG below. There are other open source initiatives on VoIP, like OpenH323, OpenGateKeeper, that were equally old or older. But that is not the point here.
Already there are a number of open source VoIP applications, such as FreeSwitch, OpenSER and YATE, that turn a computer into an IP PABX. However, the most widely deployed is Asterisk, which was developed as far back as 1999. Just one month after its acquisition of Switchvox, a provider of IP PBX phone systems for small and medium businesses, Digium announced the availability of Switchvox Free Edition. The new product is based on Asterisk, open-source telephone software created and owned by Digium."
The Asterisk was just tested by Transnexus and perhaps YG should look at those results. (Transnexus did not get paid by Digium ;) to my knowledge)