The phone company's call volume can also come into play with routing concerns. We have all digital phone lines coming from the phone company into our facility. We then route your call through our servers over more digital lines to our direct connections to the internet. Some older modems do not like this switching from analog to digital. Weather conditions - I was told this by my technicians who got it from a phone company technician, so I don't know how reliable this is but it does make sense.
Most phone lines are copper.
If you go back to Chemistry 101, remember metals expand and contract in the hot and cold. I'm not totally sure I buy this one, but it does make sense. Call waiting on a phone line - we have a lot of users with the call waiting feature. They have huge traffic on their site and downloading, viewing speeds are going to be slow. Disconnects after 20 minutes - we have an automatic feature built into our software that will automatically disconnect you after 20 minutes if the connection has not sent or received information in that timeframe.