I'm trying to pick an IP telephony technology to learn. I heard of Asterisk, trixbox, freePBX, and my head was already spinning being not sure what to learn. Then I came across this article listing some more like Kamailio, Yate, CallWeaver, FreeSWITCH, SipXecs and now my head REALLY is spinning http://www.cio.com.au/article/323016/five_open_source_ip_telephony_projects_watch .
Can someone give me a run down of how all these technologies tie together? What is the trend now, because I'd like to start learning.
Note: Anyone please re-tag this question if you know better, because I'm new to this field and not sure about the best tags.
astrisk has been around for a long time, digium (the makers of astrisk) sells cards pretty cheap for it (which are linux tested), and it is pretty easy to learn.
There is also a huge amount of documentation on it.
I would start with astrisk first.
I suggest you to start and learn FreeSWITCH. These days there are very few things in IP Telephony that cannot be realized with FreeSWITCH. In my view it's the most complete platform in terms of features and performance. Tt offers so many way to realize complex services in your favourite language, it has a wonderful modular architecture. It also has a wonderful community of users and developers, which has grown a lot since 2007. Have a look at: http://wiki.freeswitch.org/wiki/Specsheet Ciao!
The latest trend in ip telephone systems include VoIP. Instead of using traditional "circuit-switched" technology, where a dedicated path from caller to receiver is reserved for their entire conversation, VoIP phone systems treat voice transmissions as data, turning your words into tiny packets of information that are sent over a broadband network.
Here's some more information on the best telephone systems [1].
[1] http://www.phonesystemprices.com/best-phone-systems.htmlA question to your question to help us help you: how much do you know about Telephony (old school, big iron PBX-es, etc) in general? Newton's [1] is almost always a good investment; but if you're not serious about getting into that industry, save money and get an older edition.
Likely, the "Best" IP telephony for you is the IP telephony that leverages your "traditional" telephony knowledge.
Also, what is your goal? "Just to know", "I want to wire up my house" and "OMG, I have to connect four sites across three states and three time zones within the next week" all lead to different answers.
[1] http://www.google.com/search?hl=en&source=hp&q=newton%27s+telecom+dictionary&aq=f&oq=&aqi=g5Learn the overview of their capabilities first, then you'll know where you want to go for your situation. One of the best things to learn is what you don't know.