How is "an expensive frame relay type service to the internet" different than a "less expensive plain T1 to the internet"....AND how are either of these different from a private line or point-to-point T1?

Here's my opinion......

Don't worry about the technology difference between frame relay and a plain T1....or either of these and a private line or point to point T1.

A frame T1 runs at just about the same speed as a point to point T1. Much more important to worry about is what's on the other end of the circuit. If the other end of the circuit is the internet backbone, and you have 1.5M throughput to the backbone, then that's a "dedicated" connection, the best grade of service you can get. If the other end of the circuit is to a carrier's serving office, or DSLAM, or aggregation point, then the 1.5M throughput is to their equipment, not to the internet backbone, and you have a "shared" connection. A shared connection means that your provider has arranged for a bulk internet connection from a larger carrier and it splits some out for you -- but rarely do they split out your bandwidth only for you.

For example a shared provider might buy a wholesale DS-3 from Global Crossing. A DS-3 is the equivalent of 28 T1 circuits. The shared ISP would try to have many customers sharing that T1 circuit, much more than 28 customers -- that's how they make money.

Same thing with phone systems -- you might have twenty extension phones in your office, but only 5 phone lines with the phone company. This recognizes that not all users need to use the phone at the same time.

In the internet world, shared ISPs are betting that not all customers need their full bandwidth at the same time. If a shared provider pays $6000 per month for a DS-3, and sells T1s for $300/month, they break even at 20 customers. ISPs will oversell their bandwidth because not all customers need their full bandwidth at all times. If you've been reading this message for the past 15 seconds, and your PC is doing nothing else, you haven't used your bandwidth for the past now 20 seconds.

Now.....if you need the internet circuit for email, and looking at web pages, and research, a shared T1 connection is fine. But if you're running time sensitive or bandwidth hogging applications like hosting a website at your location, or if you're running VOIP applications, or streaming audio or video, or controlling machinery remotely ... then a shared T1 connection will be a big PIA (pain in the *&!) at some point during the month when the other customers will be sucking up all the bandwidth leaving you with less than you are paying for.

So don't worry about the technology of the access circuit, worry about what's on the other end. If you can get away with a shared T1 connection, you'll save some loot. If you have critical applications, then your life will be filled with drama until you get a dedicated T1 connection.