Hardware-less solution

I’m new at telephony systems and have been researching into a web-based PBX solution and the more I research the more I realize Asterisk must be the solution. However, I’m still confused as to the use/necessity of hardware.

As I understand it, the main hardware that might be needed would be the Digium cards? But I’m still not sure why I would need them…? What advantages do I have over a software-only solution if I use the hardware?
Cannot software alone do the trick?

I need the ability to automate several traditional phone calls from a website.

Thanks!

You only need hardware if you get a physical phone line (e.g. PRI, POTS etc). The advantage to “physical lines” is that they tend to me more reliable than VOIP. With VOIP there can be many more issues. On the other hand VOIP is pretty good (though not perfect). The prices for VOIP calls seem to be a lot cheaper and give you more flexibility. I would try using VOIP and see what happens.