Is Asterisk the future of telephony?

One of the early indicators of a hot new technology could be advance book sales on the topic. When it comes to Asterisk for VoIP applications, the indicators look good.

Asterisk: The Future of Telephony is due to hit the stores sometime this month. It's ranking really well on Amazon.

If Asterisk is hot, we want to know what companies are most closely associated with the Asterisk open-source PBX?

Digium is the most obvious company that comes to mind. The founder of Digium is also the founder of the initial Asterisk open-source coding project. Digium is a private company based in Huntsville, Alabama. Apparently their revenues were about $10 million over the last year. They are a very popular company and have been listed on the Pulver 100 list of top private communications technology companies for the last two years. It wouldn't surprise me too much if they were talking to venture capitalists or IPO investment bankers right now. Some extra capital could probably help them grow much faster.

Digium's closest competitor is most likely Sangoma Technologies. This is a publicly traded company that's been around for twenty years. Their annual sales seem to have been stuck at about three million or less for a few years now and their market cap is still under ten million dollars. Sangoma started issuing Asterisk compatible PCI cards earlier this year.

There seems to be some serious rivalry between Digium and Sangoma. See comments by the founders here and here.

I have been buying up shares of Sangoma for a couple of years now, so I am rooting for them. But this market is more than big enough for both. Can anyone point to more companies which are set to directly benefit from the growing popularity of Asterisk?