Some 28.8 modems have been known to have a 'spiraling death' syndrome, where they are unable to 'train up' to higher speeds when conditions improve. These speed negotiation may be transparent to the user of the modem. At best, the user may simply notice that speeds become slower and slower as time goes by. Many manufacterer's ship these upgrades for free. Line Noise and Infrequent Disconnects Infrequent disconnects may reflect a temporary change in your connection.
Weather conditions can cause temporary changes in line conditions.
Besides the obvious physical damage due to fallen tress, etc., studies have shown that excessive rain can cause increased line noise. Physical work, like construction or new line installation, can cause Bell South to temporary reroute line paths, perhaps through a noisier switch. Lowering your baud rate temporarily may allow your modem to 'weather' these changes in line condition changes. Line Noise and Lowering Speed Lowering your baud can accomplish a few things with regard to line noise. Secondly, slower speeds much less succeptable to line noise.