On the Software side of things, i guess you will need the following:
- Linux OS, which one to use is debatable, however i recommend Fedora Core 6, and immediately do an update after install otherwise when it comes to installing asterisk you may run into some troubles.
- Asterisk, if your only testing then go for version 1.4.1 and make sure to get all of the associated files with it too. Look on the right hand side under the Download section, under version 1.4 download all the files in that list to the system.
- For testing the system you will need Soft Phones, there are a couple to choose from, below are the ones you can look at and pick which one you like the most, most people choose X-lite, but you may not fall in the category of most.
That pretty much covers off the Software side of things, however if your not comfortable working with Linux on the command line level, then with Fedora install it with the GUI, for testing purposes this will not effect the system performance at all, unless the system your installing it on is dog slow. You will still need to do things on the Command Line level, but with the GUI you can easily flick through pages of tutorials whilst you have the Shell session on the tab bar.
Now for the hardware side of things:
- You will need an analogue card, there are only two worth touching in my opinion, however others can direct you to other clone cards that will be much cheaper and probably due exactly what you want, but for the sake of providing you info i will stick with what i know.
Since you are only testing, you may only want a single port one, so look for the clone cards that are out there, i think they are called the X100 or something rather like that.
Now with either cards you can probably find them second hand or pretty cheap on E-bay, do a search on your local E-bay and see what comes up for any of those cards.
Now to do SMS over PSTN, well that is tricky.
First your carrier will need to be able to do SMS over PSTN, now i am not aware of any that support that except i have heard that in Australia the incumbent Telstra have SMS over the PSTN network. However in saying that i have never heard of anyone actually being able to do it.
There are heaps of SMS type services on the internet, some even offer free SMS, i know at one stage ICQ allowed free SMS to certain mobiles in certain countries. But none_the_less if you want to put a bit of time into researching it then go for you
Anyways hope that helps you out enough.