Application for phone conversation via Landline

Some months ago, my dad wanted help blocking certain phone numbers on his landline. I had the idea that I could program a computer to block certain numbers. I found a program called PhoneTray that could block numbers with the aid of a dial-up modem. (The program is called PhoneTray Free 1.39. There is a newer version. But, since it switched companies, it hasn’t worked as well.) The thing is that would need a dial-up modem and non of our computers had RJ11 ports. So, we had to buy one. This is the first time we’d be using a dial-up model since 1999 (?). I install the program and the drivers for the adapter and it’s been blocking number ever since.

Anyways, this got me thinking. We use the PhoneTray application to block numbers because our home phone can only store so many numbers. Is there a program that can dial a number through the landline so that you can still use your home phone to talk to that person? I’m not talking about a program like Skype where it costs to call someone or you have to talk to them through your PC. I’d like to be able to pick up the phone while the PC dials the individual’s number and I can talk to them when they answer their phone.