Rule #1 - Be Patient - Rule #2 - Don't ask when, if you don't contribute - Rule #3 - You have coding skills - LinuxMCE's small brother is available: http://www.agocontrol.com
There are specific telephony cards that work, but are not PnP atm. Using regular modems is something that does not work reliable, IF at all. An external SIP ATA (that's what the SPA is), is the best solution to get regular phone lines into the system. They are fairly inexpensive, and just work.