Unless I heard wrong, a customer service agent with a DSL provider told me that my digital telephone lines cannot accommodate DSL.
She told me that DSL (Digital Signal Loop) only works with analog systems. Um, why my presumably state-of-the-art 8-wire, digital telephone line cannot handle DSL, but an old copper line telephone system can.
She added that updates are planned, but DSL is currently off-limits to folks like me.
BTW, I can’t get cable.
I’m no expert, and I hope one of them will read my post over to be sure I got things right. However, I think I know this one.
Digital Subscriber Line is implemented by transmitting a second signal on the line. The analog voice info is on a fairly low frequency, while the digital data line is high frequency. This is why when you have DSL, you have to put low-pass filters on your phones, to eliminate the high-pitched whine of the data. The DSL modem does the opposite, and filters out the low frequency to get just the data.
Since your digital line is already using a high-frequency signal to transmit the digitally-coded voice info, there’s no place for the DSL signal on your wires.
DSL stands for Digital Subscriber Line, which uses higher frequency signal on plain old twisted pair copper wiring to transmit a digital signal in addition to the POTS(Plain Old Telephone Service). If you have a digital phone line, you do not have the required analog loop to carry an ADSL/SDSL signal. The best you can probably do is to get a (possibly multiple) IDSL connection, which is a 144Kbps always-on ISDN based connection that has very little to do with regular DSL. Sorry.
I have a combined ISDN/DSL line, just like countless other people here. Actually our dominant (ex-monopolist) phone company was criticized for creating the impression that DSL was only possible with ISDN lines which are available everywhere but more expensive. However many people are effectively cut off from DSL because the phone company connected many homes directly via fiber optic lines during the 90s and currently there is no consumer broadband service for those.
Keep in mind that the entire be-all and end-all of DSL was precisely to bring some sort of wideband access to the home, *without * the unthinkable expense of upgrading the infrastructure along the Subscriber Loop.
The Subscriber Loop (the correct term, notwithstanding the other abbreviation-expansions given so far) is the part of the system that runs from the last major piece of telco equipment out to the end user. Upgrading telco equipment and the links between them is expensive, but nothing compared to rewiring every single home and office.
So DSL was invented solely to be used over the twisted-pair connections that had previously only carried voice (and a bandwidth-limited voice, to boot.) Any idea of having it exist alongside other digital technologies or being used on other transmission media was WAY down the list. It’s amazing that they were able to make it work as well as it does, considering the constraints they were designing to, and I’m not surprised it’s limited to that environment.
Because analog voice lines are limited to using only the audible frequency range there is a lot of potential bandwidth being wasted outside this band. DSL exploits this unused bandwidth.
Digital voice lines are much more efficient at using bandwidth. Once voice data has been digitized it can be transmitted at any frequency, not just the audible. Digital lines can therefore use Frequency Division Multiplexing - transmitting several conversations concurrently over the same cable by assigning each a different frequency. The downside is that there is no extra bandwidth available for data.
You’ve got fiber to the home, and they don’t offer any data service on it? That’s just shameful.
The phone company may have done this before the idea of DSL was even conceived.
‘Connected via fibre obtics’ doesn’t necessarily mean that every home has an optical connection. It means pretty much nothing. It certainly means you’re less likely to be ADSL-enabled, for the reasons given by charizard
(Yes, it would be physically possible for them to send all sorts of stuff down that fibre. But at what cost? Broadband by itself is the limit of the market. TV is restricted by all sorts of marketing. I hate to tell you things we were told in GCSE Science, but optical fibres can carry far more than anyone needs.
I just looked this up. DSL has been around since the 1980s. Thus I do find it odd that in the 1990s the telco installed fiber lines with no data service provisions.
In the 90s, ‘everything’ was going to change. DSL was only about backwards-compatibility. Anybody who claimed it would be the major form of high-speed internet access would have been laughed out of the building. New technologies and new infrastructure was all anyone was interested in.
Yep. I had an even more bizarre case. I got AT&T Digital Service to the home, and a few years later wanted to get AT&T DSL when it became available. (This was to keep our very ancient AT&T username - which is our last name with no numbers or anything. That’s how early we were.)
It was impossible for the reasons stated. I had to dump AT&T home service for SBC normal copper service in order to get AT&T DSL. It also took a while to find the reason why AT&T kept saying DSL was not available to our house.
There is plenty of bandwidth. Are optical modems too expensive, or is it screwed up at the central office somehow. When I heard people talk about fiber to the home when I worked at Bell Labs, I’m pretty sure none of them said that an advantage would be in making broadband impossible.
A valid question. And the answer is ‘yes’, when compared to the costs involved with ADSL. Everything said about DSL applies - and more so. It was specifically designed for large numbers of users across a limited bandwidth - perfect for 512k ADSL.
Yes, DSL was designed specifically to deliver high-speed data service over copper subscriber loops terminating in the central office. However, DSL is only one type of telco data service, so that doesn’t mean you will never get high-speed data service.
It’s kind of like this… in the 90’s, the telcos started switching over to fiber-based distributions instead of copper. Fiber was, and still is, the future. But when that rollout was still in its infancy, the internet boom brought the need for consumer high-speed data to a critical point. The majority of the subscriber loops were still analog copper, and DSL could exploit them. So the telcos made a full-court press to get DSL penetration on the older lines. Since the newer lines were somewhat of a minority, it didn’t make business sense to find a DSL equivalent for them. That came later, in various types of solutions generally called IFITL, DFITL, FITL-A, or FTTH which are all slightly different schemes of achieving residential broadband over fiber.
Long story short, you can’t get DSL today, but there is probably a FITL or FTTH solution scheduled for your area. Just out of curiosity, what’s your area code?
Another side issue, your digital phone service uses about 52-64kb/s to transmit your voice. DSL usually has to use up 500 kb’s, which is about 8 phone lines. Would the telco rather give you 8 phonelines worth of service for maybe $35/month, or sell 8 phone lines as phone service?
Again the main reason is a digital phone system already uses the DSL bandwidth.
But the phone company in the OPs case didn’t use any “new technology” that had future possibilities for high-speed Internet access. Why bother in the 1990s abandoning copper lines with something that had even less potential for Internet access?
Actually, fiber has even more potential for high-speed bandwidth than copper. But these technologies haven’t been developed because when the bandwidth boom hit, most customers were still on copper. Telcos had a choice between providing a fairly good solution to many customers or giving an amazing solution to a handful of customers. With the cable modem threat nipping at their heels, predictably they chose to enter the market sooner with the technology that was available. So the early adopters of fiber suffered, although they’ll be more satisfied pretty soon when the fiber technologies become more widespread.