iLocus studied the VoIP market from 1995 onwards and selected certain developments within the industry that helped establish it and related those developments with 10 selected companies.
Source: VOIP IP Telephony: Who established VoIP? here is 10 of them!
As an implementation of SIP and various media protocols, VoIP is still the main application area for pjsip (although recently Audio-over-IP has adopted SIP as well). So it is very interesting to have a recap of the last decade or so on how we all came to know (and love) VoIP.
What do you think? Tell us your “moment” of VoIP!
pjsip blog 
Nice introdution to VoIP history here. Thanks for the post.