Well..this depends on a few things.
1) Is your modem a 56k modem?
2) Is the speed set at the maximum?
3) Is the modem new?
4) Did you experience a recent thunderstorm?
5) Are you living in a very small town?
I ask because I live in a town that is, for all intents and purposes, dead! So my Internet Provider doesn't really pay much attention to the quality of service to a dead town.
Also, did you talk to your provider? Be careful though as they love to pin all the blame on you..it happened to me quite a bit.
Also..ask your phone service provider too..they may be having problems with their trunk lines.
Furthermore, nearby radios, T.V's and other electronics and even transmission stations can interfere.