dslreports logo

    All FAQs Site FAQ DSL FAQ Cable Tech About DSL Distance DSL Hurdles »»


how-to block ads

To understand the differences in the speeds seen by different people, I'll explain the different capping methods used by SBC/ASI. There are a few things to touch on about DSL that will help you understand.

DSL is a frequency based transport, utilizing the frequency ranges that are beyond the POTS(plain old telephone service) ranges. POTS utilizes the human audible range of 0-4khz. DSL, as far as ADSL, starts at 20-100khz for the upload band and then again at 120khz-1.1mhz for the download band. This is important because then longer the copper loop is, the higher frequencies drop out, causing a loss of available bandwidth. Now what this means in layman's terms:

If you're on a long loop, then the DSLAAM/modem connection won't be able to sustain a maximum throughput to keep the line up in sync. To correct this, the DSLAAM is re-programmed to only transmit at a bandwidth that can be sustained reliably.

The 3 major caps are 384k, 768k and open which is 1536k. Keep in mind, that IF you can sustain an open 1536 line, you can probably sustain the higher speed Option 2(1.5-6.0M/384kpbs) line, although in some situations the cost WILL outweigh the gain as far as download speeds.

Now, as far as the newer 192/128 lines. SBC, wanting to provide DSL service to those who were not able to sustain a 384/128 line, came out with a new package. This would let customers have a faster connection than ISDN at a discount price. This was implemented for those customers who were beyond 14kft, which was the point were dramatic decreases were seen. The lines were set up to be automatically raised to the best speed possible, using monitoring software to set the limits.

1) If you are a new customer and are seeing speeds in the 120-150/128 ranges then you can be certain that you fall under the 192/128 plan that will gradually increase your download speed up to the best that can be achieved by your line.

Two notes to read:

.....A) You will start out at 192/128 no matter what your line will handle. In time, usually in 6-10 days, the monitoring software will analyze your line history and raise your speed in increments to the best speed your line will sustain.

.....B) If you were signed up on this package WITHOUT knowing about it then you'll need to contact your ISP and complain very loudly, my advice only!

2) Your line CAN be uncapped to it's best speed, but it won't happen through the normal Tech Support channels! My advice is to seek out one of the techs who frequent the forum, IM them with your DSL number and see what they can do.

Let me repeat, normal tech support will not be able to do anything! Enough said.

3) If you're seeing speeds that you think are low then visit this link and run the Tweak Test to make sure your computer is optimized for a broadband connection. If you still need help then visit this link and click on the above *here* to follow and answer the questions needed to get your DSL line up to par.


4) If you're still seeing speeds below what you think you should be having then I recommend you visit the Tweak forum at this here. Answer the 11 questions and we'll be glad to get you up to speed.

Yes, the above will lead you to the same place eventually. This just makes sure you have followed the steps to make sure your line is optimized to it's best possible outcome depending on your line conditions.

5) If you're an existing customer and have already tweaked for a broadband connection and still sees dramatic decreases in your download speed then by all means, IM one of the techs here on this board who can look into this problem. I won't list them here, but an IM to Flippant or one of the other regular posters will set you in the right direction.

Expand got feedback?

by kmac1 See Profile edited by Flippant See Profile
last modified: 2002-06-05 23:01:03