64k on POTS

Yes it can and is possible; howerver, the modem is just lying to you, that's all... I've even seen connection speeds up 128kb on standard telephone lines! If you do a throughput test, its effective communications rate is only around 35kb - 40kb at the most!

What causes it? On my machine, it was a standard (generic) modem driver used to run a specific modem. It could also be that the modems on both ends are not 100% compatible.

Try sending a file across both computers and calculate the bit/sec and you'll see. Send something that's bigger than 100kb to get a more acurate rating. Here's the formula:

size of file in bytes / download seconds * 8 = bps

The bandwidth of the POTS is 64k.
The new 56k modems are designed to recognize and 8-bit digital symbol 8000 times a second (8000 symbols x 8 bits per symbol = 64k) .
But since some telephone serivces in North America use one of those 8 bits for control purposes so users can only use 7 bits. (7 x 8000 = 56k)

Then theres line noise which cannot be avoided. I saw somewhere that in Atlanta 56k modems connect at less than 40k 18% of the time, 40-50k 80% of the time, and more than that on 2% of the time.

The further you are away from your CO and the more little green boxes your line goes through the more noise your line will have and the worse your connection will be.

That's the low-down on the phone lines. Waht I dont knwo is why modems liek to tell you they're connecting faster than possible. I've been conencted up to 112k before. Who needs DSL? :)

Brian Wright
Computer Information Systems student
Terra Community College
Fremont, Ohio