Hi,
It's more than likely the phone company. This happens lots where I live and the only way I was able to get around it was to get cable internet or DSL. The phone lines here are spliced so much that even tho i am real close to the phone co I cannot get better than 38 kb speed. The phone lines are 70 years old here! And they are pathetic! Dropped connections galore. I don't know how I lived on dial up before cable or Dsl!
Oh I used to have two phone lines and I used two modems by multilink bonding them and i was getting 75 kb connections at times! So I borrowed a phone line from a neighbor as a test and ran three modems and got over 110 kb speed. Of course your Isp and your os must support Multilink bonding! 
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If it ain't broke, you arn't trying hard enough!!
If it ain't broke, you arn't trying hard enough!!