Make life easy.
Forget Ubuntoooooooo, at first. You can always go back to it when you get some time under your belt with Asterisk.
1: Just download the latest “stable” version of *Now, install on a machine you don’t mind setting aside just for your phone system,
2: before you buy any cards get it working with a couple of softphones between two computers, once you know you have it up and running then you can buy a new or used digium fxo card or go on e-bay, type in digium in the search bar and you will see a bunch of different sellers pop up with different cards for sale, there is one I use that was $29.95 US money, claimed to be the real one, and it works great, can’t beat 29.95 when the other are 100 or more. It’s sold from somewhere in asia, if you need name let me know and I will dig it out,
3: make a few phone calls with it, if all works then get some VoIp phones and place them in ur hose and try,
4: since you have dsl at ur house and mom’s then take one of your new found VoIp phones over to mom’s, plug it in and wala, it should find your box (if you programmed it right). Mom can now make calls off your box and mom can give your number out with her personal extension number. That is the way I have all my family set up, three in Texas, one in Florida, and the rest in Calif. We have one phone bill (actually have 12 lines) and we can take them anywhere with us on the road or to a new house/location.
For info, and to save you a lot of time:
1: if you have dsl, get into your dsl router and find your dynamic address of the router as you will need this for your “outside” phone to know where to go when looking for your machine.
2: make sure that you have the required ports “open” on your router ( generally port 5060 and 1000-2000) and that your dsl router knows to forward these incoming to your in-house machine.
3: Remember when using dsl, your dynamic address can change at a minutes notice, so be prepared for this when it happens, I have static ip, but I also pay for it as I have web server and other servers running on that ip address.
Once you have it all set up, then take and place ur cell phone as one of your extensions and if you have one of the new cell phones that does sip/voip/wifi then you could use any local wifi town and use your cell phone to make free calls off you machine through wifi while out and about.
Now that you have all this going then you can get another machine put ubuntooooooooo on it and download asterisk and hard code and setup your stuff on it.
One other thing you may want to play with is using your in-house portable phone with your asterisk machine, thus giving you the ability to walk around the house and using sip at the same time. You can buy portable phones at the garage sales or new for less than 50 bucks US money.
I use cordless phone at all locations and even have one mounted in my car attached to in-car termanl laptop.
As the mind wonders, fun things come about.
Have fun trying Asterisk and good luck.