If you have dialup you need to check call answering service with your phone company, etc. My friend was in dial up hell till we found the phone company charges an extra $9 for dial up service, he was getting less than 18 kbps till they fixed it; now he gets better than me; about 53 kbps and he stays on line; before he couldn't. I'm just saying you phone line can have everything to do with it. First check the line with a computer you know does well, and if it does horribly on that line you know it is the line. Next tell the phone company; if they are like my service they have a line for regular phones, which may or may not sound scratchy at times, or they can fix that line for dialup for about 9 bucks extra.
Even my 667 DVI does terrific at home, but out of town in motels the line may be so bad I get continually cut off or I cant even get online.