I got a great story that goes along with this topic sort of... I'll get to that after I answer your question. About 2 years ago I bought a DID with Oooma to use as my home line. I decided Ooma sucked and ported my number over to voip.ms and connected an ATA box to my analog cordless handset. I think I pre-paided $25 when I switched to voip.ms, and I still have $12.12 in my current balance. There is no need for a FreePBX for your grandparents and parents if you go with voip.ms. However, feel free to set it up if you really want to practice and have something to play and test with.
Now, back to the story. The number I purchased with Ooma was like a business line because it ended with 8000. It was easy to remember, which is why I bought it. About a year ago I started getting calls asking if they are calling a Dentist office. I kept telling callers they have the wrong number. Finally, the owner of a Dentist office calls me and says they had just bought my home DID from Ooma. She explained that the number was already published on all their brochures, insurance documents, and all their phone extensions were based off the 8000 extension etc... They were also opening in 2 weeks. Turns out Ooma never removed the number out of their database when I ported over to voip.ms and then sold the number to this Dental office because they bought Oooma Business phone service. I mean there was only two people that called my home #, my mom and my dad. And this business was screwed. The cost to change the DID on all there brochures, documents, etc... would probably cost them a good amount. The Dental office ended up making me a $$$ offer for the DID and I released it to them. The owner was also a Dental surgeon and offered to do any Dental surgeries for my family with no out of pocket costs after insurance pays. Turns out my wife needs gum grafting surgery and we are going to save another $1,000 - $2,000 dollars by not having to pay anything out of pocket after insurance. I mean what luck. I love telling this story. Sorry to side track this thread, but it just reminded my of this.