It costs us less to bring Internet bandwidth here from Philadelphia where we connect to the main Internet than it does to distribute the bandwidth to our users once it's here.It's this high cost of local distribution that is the vexing problem facing the Internet today. It's bad enough for distribution at dialup speeds, and it's even worse for distribution at high speeds.
DSL is a partial solution to this "last mile" problem. It is only a partial solution because it can't be used for everyone.
The telephone network has the huge amount of bandwidth needed to carry a town's worth of digitized phone calls to each town, and getting digital data to a town is relatively easy and cheap. However, it winds up in the town's telephone switching office. The last-mile problem is getting digital data from central telephone offices to end users.Telephone lines are wires that run from the central telephone office to individual users. It has been known for decades that these wires are inherently capable of carrying high-speed data, but until recently the cost has been prohibitive except for special applications.
DSL is a technology - a relatively new and relatively low-cost technology - for rapid (megabit) data transmission over these ordinary phone line wires. The DSL concept is that DSL technology running on phone line wires connects you to your local telephone office. Your ISP also connects to your local telephone office by some means (usually not by DSL), and the overall effect is to connect you to your ISP and, through your ISP, to the Internet.
Your computer (or your network) then is permanently connected to the Internet at high speed. Unlike dialup, DSL does not require anything resembling a "call." You remain connected as long as the DSL equipment has power.
DSL comes in many different types suited for different kinds of service, but only two types are in common use for low cost Internet service.ADSL is Asymmetric DSL, meaning the download speed is greater than the upload speed, similar to cable-modem service. ADSL also is designed to co-exist on a phone line with telephone service. The line can be used to make or receive phone calls while being used for Internet access, and ADSL service can be installed without installing a separate phone line for it. The reduced upload speed can be a significant limitation for users who want to run a server or who want to stream outgoing data such as video or audio. ADSL is almost universally used for residential DSL.
SDSL is Symmetric DSL, with the speed the same in both directions. There are several subtypes of SDSL that differ in speed and technology details too complex to go into here. The most advanced subtype is capable of speeds as high as 2.3 Mbps under good conditions. SDSL is particularly well-suited to businesses.
Phone lines go everywhere, but DSL doesn't. DSL works well only on phone lines that are relatively short. DSL speed begins dropping off rapidly for line lengths much in excess of a mile, and DSL reaches its limit at about 3.5 miles.(It's possible to extend the limit by using special DSL versions and modifying longer phone lines. However, it's the use of existing phone lines without special treatment that underlies DSL being low cost. Also, these long-distance DSLs have greatly reduced speed.)
As people come and go over years, phone wires accumulate leftover sidebranches that are rarely ever disconnected when no longer needed. These cause problems for DSL and can be a more important limitation than line length. Longer lines tend to have more side branches so the two limitations tend to work together.
These limitations still leave a lot of people within DSL range. They make DSL particularly well-adapted to providing Internet service to businesses collected together in town centers near the local telephone office.
We have never sold non-business accounts, so businesses are our primary market, almost our only market. DSL being well-suited to serving businesses fits us well.On the other hand, we've also focused on service to remoter areas, so the "in-town" limitation makes DSL something of a quandary for us. It is inherently unusable for service to many of our past and existing users. In addition, other factors prevent us from offering it even to our in-town customers in towns other than Saratoga Springs. Those factors involve how DSL service is structured.
When you make a telephone call, you're using the telephone company's wires, but you're also using a service, telephone service, from the telephone company. (For people close to their telephone office, it's the telephone service, not the wires, that limits dialup to speeds far slower than DSL.)Similarly, one way for DSL to be deployed is for the telephone company to provide both wires and DSL service. Then ISPs can provide Internet access using this telephone company DSL service just as they provide dialup Internet access using telephone service.
Verizon does provide such a DSL service, but it is highly structured toward very large ISPs. Ironically, they provide both a low-cost way of getting data to telephone offices (frame relay) and a low-cost way of getting data from the telephone offices to end users (ADSL). The catch is that they don't let these be used together.
There are parts of the country where the local phone company provides both and does let them be used together. In those places small ISPs can use telephone company DSL to reach end users. (If Verizon allowed this, we could provide low-cost DSL throughout most of our normal service area.)
A second way an ISP can deploy DSL is to get direct access to the wires and generate it's own DSL service. This requires that the ISP locate equipment inside the telephone company offices, and doing that requires legally becoming a telephone company. Although NY State makes this unusually easy, it too is beyond our reach.
There is one way we can get access to telephone company wires, but it's at our premises, not in the telephone company offices. We can lease a circuit from the telephone company that consists of two phone lines, one from the telephone company office to us and one to our user, with the two lines connected together in the telephone office.Such circuits were originally intended for fire and burglar alarms, but we can run our own DSL (SDSL) service on them and use it to provide Internet service in Saratoga Springs, to locations reasonably close to the telephone office (at the corner of Phila and Putnam, basically right in the center of town).
The best locations for this DSL are places within about a mile; locations farther out gradually become less well-suited to DSL. Our fastest line (2.3 Mbps) is to a location three blocks in from the hospital. Our oldest circuit has been in service since July 1999, reliably running at 1.5 Mbps.
These two-line circuits are expensive, partly because we have to pay for both lines. In fact, Verizon sells single-line ADSL circuits plus their own Internet service for less than they charge us for just these circuits. The cost of these circuits prevents us from competing with Verizon or anyone else for low-end accounts. It limits us business and commercial customers. This is a natural fit for us though; we have never sold non-business accounts.
This alarm-line DSL is only possible where the telephone office serving us is the same one serving our user, so we can only use this where we have a physical location. It's this limitation that prevents us from providing DSL in Glens Falls. Our Glens Falls location is actually in Hudson Falls, which has its own telephone office.In principle we could provide DSL in Hudson Falls However, the length of an alarm circuit is the sum of the lengths of the two lines joined to form it, and our site is too far from the Hudson Falls telephone office for good DSL. We had a test line installed there, and it worked surprisingly well but not well enough for us to market DSL in Hudson Falls.
The last limitation is that the telephone company must be willing to provide circuits for this use. Verizon is, but Citizens is not. That prevents us from providing DSL in North Creek. Of our three physical locations, the only one where we really can provide DSL is Saratoga Springs.
DSL providers registering as phone companies and trying to provide widespread DSL have to place expensive equipment in many telephone offices. This is a huge upfront expense and is why several have gone out of business.We can instead use small-scale devices and provision one line at a time. That way we don't have to buy the equipment until we have a customer for the service. That's a significant advantage, enough to make this alarm-line DSL a viable way for a small ISP to ease into being a DSL provider.
The equipment for each line is expensive enough that we can't afford grow our DSL business too rapidly. This is why we did not post any mention of DSL for more than a year after we began selling it, and we continue to be cautious about how many orders we accept.