Your ISP and You...

[ChrisPerry]

Get a booster for your cable. Runs $60 or so, somtimes called a line amp or amplifier.
IN theory, the cable company will deliver enough signal to you that you shouldn't have a problem. However, a low signal can come and go if htere is a weak connection someplace (a cable end inside or outside your house) as there are extra loads on the line (more users, and since teh TV signa is on the same cable, the number of TVs in your house can effect this, or even on your block!).
Also, being a network, the more users on your line (neighbors, etc) the slower things can get, especially if you've got some heavy user and you're line is at the limit of users/bandwidth/signal strength.

I added an amp and things got a LOT more reliable. No issues until a month or two ago when they turned on the new neighborhood across the street, and I got 3 new neighbors (4 users total). The new neighbors have kids and are normal age - the previous folks were 80+ (and unlikely to be broadband users).

My upload speed died...too slow for my vonage to work (need 300K..I had about 225 a lot of the time). Comcast says 'up to 768 upload'..it's the UP TO part that keeps them out of trouble.

I called and found out for $10 a month more I could get the top of the line stuff, which I don't think is as fast as they claim, it's got me around 2Mb upload - a hell of a lot faster than before. DL speed was around 5 to 6, and should no be as high as 12 or 16 or something...my measurement isn't that high, but it's not been an issue as I don't download movies or anything huge.

[pumpdog]

Well, I think I'm up and running for good now. After over a year of complaints they finally traced the problem back to the outdoor boxs throughout my neighborhood, they have signal boosters in them and they were not properly calibrated, tuned in, set correctly...whatever the correct term is.