Asterisk and VOIP

Hello, I am looking to get some technical information regarding my future Asterisk implimentation. Here is what I want to do. I would like to configure my system with no traditional TDM equipment, strictly voip(sip). What would I need to do as far as outbound/inbound? Meaining can I integrate this with a voip service like skype/vonage without incurring additional cost or would I be better off purchasing a sip trunk from my local provider (Verizon). If I went the sip trunk method is there a specific way to integrate this, more over is there a specific way to use asterisk without a T1/E1 card or any other type of hardware?

My goal is to build an Asterisk box using existing servers, I do not currently use a VOIP service provider and I am wondering how I would integrate my Asterisk box with that provider. Can this be done and if so what service providers should I approach?

Thanks

I run Asterisk with only VoIP. I buy inbound calling (this is known as SIP origination service) from one of the many SIP DID providers. You can buy a phone number and configure it to route to your SIP server – you can also get free numbers, but they’re probably not in your local area code. I use didforsale.com but there are plenty of competing providers. For a local number, expect to spend between $5 and $10 per month, usually with unlimited usage.

For outbound service, you’re looking for SIP termination providers. I use flowroute.com but here, also, you should shop around. Rates are usually around a penny per minute.

For extension telephones, use VoIP phones from Cisco, Polycom, Grandstream, etc., or use ATA’s from Linksys, Grandstream, or the like, and plug in a plain old analog telephone set.

The PC running Asterisk needs nothing more than an ethernet interface.