If you have a choice between getting your broadband from Big Telephone Company Inc. and Mom and Pop’s Friendly DSL, you may think that there’s more of a difference between the two than there really is.
Sure, they may offer different plans and different pricing, and you can be fairly certain that Mom and Pop will give you more personal attention, but there’s a very good chance that both are giving you the same internet connection.
For one thing, there are only so many ways to physically connect to the internet. There are telephone lines, coaxial cable, fiber optic cable, and various wireless solutions (broadband satellite, WiFi, 3G, etc.). Just as you can have several local and long distance phone companies using the same telephone lines, you can also have different ISPs sharing the same infrastructure that connects your home to the internet.
It’s not uncommon for an area to have only one ISP per type of connection. For example, there are many places in which only the local cable company offers broadband internet access on coaxial cable. On the other hand, there are also many places that have two or more ISPs sharing the telephone lines.
Think about dial-up ISPs: they’re all using that same telephone line, so there could theoretically be as many different dial-up ISPs as there are numbers for your modem to call. The details of DSL are a little different (to put it mildly), but the principle is generally the same — you could have multiple ADSL connections all running through the same telephone lines to your home. And obviously all wireless connections use the same air!
In addition to the physical connections, there are the non-physical connections. It can get a little more complicated when you talk about things like “routes,” “transit,” and “peering,” but basically it’s all about how your ISPs connect to other ISPs, to connect to the internet.
When you think of an internet Service Provider, you generally think of the companies that you pay to connect your home or business to the internet. These are referred to as “Access ISPs,” but they themselves go through another set of ISPs (called “Upstream” or “Transit” ISPs) to connect to the internet. Ultimately, this increasingly complex food chain of ISPs ends at what is called a “Tier 1 ISP,” which doesn’t need to go through anybody else.
The important thing to keep in mind is that anybody that can give you an internet connection is paying for their own connection — and that includes the smaller local ISPs as well as the big ones. The only real difference is that many of the big ISPs are part of the same companies that are generally considered to be Tier 1 ISPs, such as AT&T, CenturyLink, Sprint, and Verizon. But even they still have to connect their access ISPs to their upstream ISPs.
Look at it this way: it’s a little like choosing between going to the post office, or going to one of those little mailbox stores — either way, the same postal service is going to end up delivering your package. Although there may be great reasons to choose Mom & Pop’s Friendly DSL as your ISP, they’re still probably paying Big Telephone Company Inc. to use their internet connection somewhere along the line.