When I first wrote about Asterisk, the open, Linux based PBX it was for the January issue of Internet Telephony Magazine. I expected Asterisk to do well but I didnt expect the groundswell of activity that I have recently witnessed. For example, at our Internet Telephony show last February in Miami, their booth was mobbed. At our VoIP Developer show last August in San Jose, once again their booth was mobbed and their networking reception had steady traffic, including many people that drove down from Linux World which was taking place in San Francisco the same week.
I am sure they will once again be mobbed in LA, where Internet Telephony Conference & Expo will take place in less October 4-7. This week the company is busy with the AstriCon event which is taking place in Atlanta. I understand there are over 350 people signed up to attend the event which is quite impressive.
I just learned that Tom Keating blogged that Asterisk was announcing version 1.0 of their product at this event. Open source telephony is gaining momentum and Digium/Asterisk is on the cutting edge. You definitely want to get to this event to learn more about what open source can provide you.