Asterisk is better to raise on FreeBSD or Linux?

IMHO it's easier to use a pre-assemblies (such as trixbox is based on CentOS). Let me explain why. Because the finished Assembly is tested for compatibility all modules, if you want to upgrade to new versions with high probability none of the configs will not break and everything will still work.
But it is important load. 20-30 calls we are kept quiet on P4. If you plan a big load, redundancy, etc. then Yes, it is better to configure everything from scratch yourself.

Yes, it skilso. Need help — contact us on forum.asterisk.ru — there are many specialists on Asterisk, which is more than the subject.

Over time, I think the system will grow, not only will need recording 8-12 calls. As the platform you intend to take IBM x3200 M3(4 Gb RAM, 2 SATA HDD), I think this will be enough even if the system will increase in two times.
Tend, nevertheless, to the choice in favor of Linux. As I understand it linux native )

Linux by far.
\r
If sumlevayus — read the forums asterisknow, in which fans of freah faced with unusual problems. Their forums are called FreeBSDM providers, as true lovers of bdsm.

Ah thanks!
\rasterisk-support.ru you know, here's another forum, hood.

My friend is an expert on Asterisk, using Debian and says that it suggest the developers themselves.
\r
In General, looking under what tasks, if you just call the server to handle any OS.

Choosing Linux is already done, the guys on the second part of the question, note =))
With iron there is some uncertainty.