Sick of Paying so Much to our Local Phone Co

i see opportunity to decrease how much we pay each month to the local phone company.
we currently have 5 pots lines at our office and pay way too much. i would like to do a proof of concept by 1st purchasing an IP phone (maybe cisco, linksys or other suggested), build out a linux box w/ asterisk running on it then get my hands on some phone numbers.

i think this is how it works but please correct me if i’m wrong.
again, the initial step would be proof of concept to make sure it will work across our very slow DSL line of 512k up by 1MB down.
if i’m thinking correctly, could someone tell me where i should start?

The best place to start is to read the book: http://www.google.com/url?sa=t&source=web&cd=1&sqi=2&ved=0CBkQFjAA&url=http%3A%2F%2Fcachefly.oreilly.com%2Fbooks%2F9780596510480.pdf&rct=j&q=Asterisk%20the%20Future%20of%20Telephony%20pdf&ei=l-n4TPSDNYGCngfG0ZitCQ&usg=AFQjCNHpFxWF00fmkR8bYuVF65wobfT-qw&cad=rja. It’s somewhat out of date now, in particular references to zaptel should be replaced by DAHDI and the versions cited are not current, but the majority of it is still relevant.

Also, if you are planning on sharing your DSL line with voice and non-voice traffic (web, email etc.) then I would advise getting a router that has QoS to prioritize traffic based on ToS/CoS settings, especially if you have a slow connection.

In addition, I have found that the quality of the handsets makes a huge difference to the user experience -don’t skimp on them by going for the cheapest.

Good luck,
Ian