Asterisk is an open source phone server used predominately in business to route incoming calls through those awful menus to the person that should know how to deal with them. The usefulness of something that can do pretty much anything you could think of with phone calls is obvious for companies that deal with a large number of calls per day. Something that gets less mentions in using something like Asterisk for a home phone system.
Why should I?
In one word, flexibility. Some of the things you could quite easily do with a bit of dialplan magic:
- Maintain a block list of callers
- Make private numbers need to press a button before the phones ring
- Only ring the bedroom phone before 23:00
- Email an mp3 of a voicemail message to your inbox
- Use your mobile phone as a handset for your home number when connected to the WiFi
- Have multiple phone numbers with different rules for each one
- Connect to and use your home phone number from anywhere that has a internet connection, including to receive calls
- Keep logs of all the calls made forever
- Record all the calls that go through the server
- Receive fax documents - woohoo
These are just a few things I thought of in the 15 minutes I spent writing the first part of this post. The dialplan can call an external script so I think you'd struggle to think of something that can't be done.
There is also the cost, which is much lower, there is no line rental nonsense and you just pay a rate on the calls you make. Okay the cost per minute is sometimes higher than a traditional provider, it depends what you need.
What's to stop me?
Like anything there are a few counter points.
One of the main things that is making this hard for me is that it's quite hard to find a SIP phone that does not look like it belongs in a gloomy office of a company that sells beige envelopes. With a bit of hunting a nice one can be found, but it will cost about ten times as much as a conventional phone. Most SIP phones that can be found link to a base station, if like me you're after a phone that uses WiFi only you need to search for "SIP WiFi phone". VoipSupply has a nice selection to give you an idea of what to look for.
Another big issue for some people will be that you need a server to Asterisk on, pretty much any old computer will do for this as long as you don't make hundreds of calls at once.
You're technically supposed to have a conventional line too so you can always contact the emergency services, although I'm not too sure why BT is thought to be more reliable than the internet.
On most Linux servers it's really easy to install, on Ubuntu it's done with a simple apt-get
apt-get install asterisk
Okay setting it up and configuring extensions and peers is a bit more work, but that's not really the point of this post.
Final summing up
I like the idea a lot as it lets quite cool things happen without being intrusive, in that someone who is not very computer-y would be able to use the phone without really knowing the difference. But is it really worth it considering that most people just use their mobile phones for calls these days? I'd say so if you find this sort of thing fun.