It is probably the phone line. If you have checked all of your connections inside the house, (remember another phone on the same line can knock you off your internet connection) and they are all good then it is most likely a problem in the phone line on the phone company's side.
We used to have a similiar problem, everytime it would rain our line would get bad and we'd lose the connection. There was a problem in the phone line where a tree branch had rubbed through to bare wire.
If you are getting dropped like after 2 hours or 4 hours, it could be your ISP bumping you, or, you may need to check your settings to see that you're not being dropped because you have it set to drop the connection after being inactive for for 30 minutes or an hour or whatever.
The log is just basically showing that you lost the connection on your end though, if your ISP was disconnecting you intentionally there would be no such log entry. It would say something like "your account has been logged off due to inactivity"
When using a modem to access on-line services, there will almost invariably be an occasional disconnection. If this is a chronic problem for you, this document will help you find out what's causing the disconnections, and what you can do about fixing it.
One of the most common reasons for disconnection problems is line noise. When there is extended static or noise on a phone line, or the signal becomes very weak, the two modems exchanging data can't "understand" each other. Most modems will pause when there is noise on the line and wait to recover the connection, but occasionally this is not possible, and the modems will disconnect from each other.
From USR's web site:
"Dropped connections can occur when there is a sharp decrease in line quality during a call. [28.8] modems will switch to rates as low as 4800 bps to compensate for these changes. If the loss of quality is extremely severe, they will drop the connection."
There are often severe changes in line conditions during and after inclement weather: moisture in the ground caused by storms, flooding or snowfall will typically make connections less reliable. There are many other conditions that might affect line quality: if you have tried all of our suggestions in this document and still experience disconnect problems, you may want to contact your telephone company's repair department.
For maximum line quality, CoreComm uses what are known as channelized T1 lines on most of our connections. These digital lines, similar to ISDN lines not only allow us to offer 56k service, but are also not as susceptible to the types of noise and signal problems that are common with standard analog lines.
Some older 28.8 modems are not as capable of holding connections with bad line conditions: these are known as v.FC modems. If you have a modem that supports v.FC but not v.34 for 28.8 connections, that may be the cause of your problem. You can get this information out of your modem's manual. Most modem manufacturers offer an upgrade that will allow you to upgrade your v.FC modem to a v.FC/v.34 compatible or even to the new V.90 standard; contact your modem's manufacturer for details.
Also, there are often occasions where the firmware for a particular modem (i.e., the software that "runs" the modem) is prone to disconnects. In the past, problems of this sort have appeared with Supra firmware upgrades to turn their 28.8 modems into 33.6 modems, and on early X2 modem models. If you are experiencing disconnects and have either a new modem or recently updated your modem's firmware, you might want to check with your modem manufacturer to see if a fix, updated firmware, or updated software has been released.
Another common reason for lost connections is call waiting - the call waiting "beep" on the line is interpreted by modems as noise on the line, and can eventually cause a disconnection. In most areas, you can turn off call waiting by adding *70, before the CoreComm phone number (if this does not work, check with your local carrier about the procedure to turn off call waiting while on the Internet).
Inactivity can also cause disconnections. CoreComm has a 20 minute inactivity timeout, meaning that if you do not send any data over your Internet connection for twenty minutes, your connection will be dropped. When you type a message in your mail program (say, Netscape or Eudora), it's not actually sending any information out over the Internet until you actually click on the send button to send the final message out. Most Internet dialer programs will automatically drop the network connection after a few minutes of inactivity. The best way to get around this is by using a "ping" client, which will send small, unobtrusive packets of data across the Internet to keep the connection alive.
Windows 95, 98, and NT4.0 all include a ping client: you can use it by opening up a MS-DOS Prompt and typing in 'ping -t core.com' and hitting enter. Minimize the window, and your connection will remain active.
If the disconnections are occurring at times when you're certain you're not inactive (such as file transfers), the problem may be linked to the hardware handshaking configuration of your modem: try adding &K3 to your modem's init string to force this feature on.
If you are connected for over 8 hours, you may be disconnected in order to be fair to our other customers. Simply dial back in if you need to continue to use the system.
Also, by default, all dial in accounts only allow ONE concurrent connection online. So, if you are online your account, and someone else tries to log on with your account, you may get disconnected. Make sure you are the ONLY person logging on to your account and you should be ok.
Some modems are better than others at holding connections. We've rarely seen problems with US Robotics brand modems (except one particular model -- see the section on RPI below) or Motorola's. Modems that use the Rockwell chipset. However, some are more likely to sporadically disconnect: modems by Hayes (esp. Hayes Accura), Zoom and Practical Peripherals, and software modems, such as the LT WinModem and HSP modems are more likely to experience problems of this sort.
Other modems, known as RPI modems, don't have error correction built into the modem: you need special RPI drivers. If you have an RPI modem -- the two most common are the USR Sportster SI (not to be confused with the standard Sportster FaxModem) and the Zoom 14.4 PC -- but aren't running the WinRPI drivers, that's likely the problem.
Some older cordless phone and fax machines use capacitors, which are prone to send surges of electricity across the phone connections that those units are attached to: such a surge can easily knock a modem user off-line. If all of the above measures have failed, you may want to disconnect all of your other phone and fax equipment from the line for testing to see if possibly one of your other telecommunication devices is knocking you offline.