I've made some progress with my Asterisk PBX planning. As I indicated earlier, I had to do a re-install of the operating system on my backup server (From FreeBSD to CentOS) first, and I've managed to get that out of the way. I've also developed a strong appreciation and respect for the "yum" package manager. It's very good, and as easy to use as ports on FreeBSD.
Anyway, I've begun the work necessary to build a simple PBX system at home, using Asterisk. I figure I'll practice at home, and if it works well, eventually migrate my business onto the same system. At this point, it's largely reading and research, as I have to (gasp) actually purchase some hardware in order to make this work.
Apparently, I'm going to need a PSTN interface card.
For those not in the know (like me, up until recently), PSTN stands for Public Switched Telephone Network. Also, POTS is Plain Old Telephone Service. And in case you were wondering, PBX stands for Private Branch eXchange. Wikipedia has some great info on the history of the PBX.
I'm sorry for the digression.
A PSTN interface card is the basic device that permits you to connect analog or digital phone lines (the ones that you use at work or at home to connect regular phones to) to your PBX. Once you've done that you have access to all the nifty features that Asterisk offers, such as call parking, voice mail, and so forth.
There is a helpful site found here that details all of the various cards known to work well with Asterisk. I'm going to have to do some serious price comparison for awhile, and find one known to work well with my system.
This is going to take awhile.