Your best bet is to start a Skype account. In the upgraded account, it will cost $3 per month, and you are able to make unlimited calls throughout the US, if you are in the US. I use my account on a DSL 1.5mbps, and get great reception. It will cost $24 extra for a new portable number that has your area code, and if you have an analog phone, there is a device called ‘VoSKY’ which will convert VoIP digital to analog.
You can sign up for free on Skype, and make Skype to Skype calls for free. Also, you can IM. If you do so, search for new (add) contacts, and find my account (jospmoran). I will help you config your account.
Hope this helps,