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Lost carriers occur when the client end (your computer), of an internet connection disconnects without a user request (the user has not chosen to disconnect using standard disconnection methods). The telephone exchange then tells our access server that the call has been terminated, the client's session ends and is recorded with "Lost-Carrier".

The most common cause of a Lost-Carrier is noise or weaknesses on the phone line.

Unlike voice, data is extremely sensitive to noise on the line. Although you may not hear noise on the line because it is inaudible to the ear, a modem will always pick it up. Some modems are able to handle a limited amount of line noise (such as the US Robotics range) and still stay connected, whereas a lot of other modems will drop a connection if they encounter any line noise. The three most common types of line noise are:

  • Crackle (audible).
    • the insulation around the copper wire breaking down and allowing the wire to lightly touch another wire.
    • damage to the cable sheathing can allow moisture to get in to the wires, when the cable dries out it causes crackling on the line.
  • Hum (varies from audible to inaudible).
    • caused when cable sheathing deteriorates and voltage from the line either seeps into another or dissipates into the surrounding earth. This is usually hard to detect.
  • Click (audible)
    • usually found in rural areas where telephone line has been laid under or around Electric Fences. Older washing machines may also cause a click on a line.
Internal modems generally do not have the same robust qualities as external modems. The most common internal modem is a Lucent (LT WinModem). Slowing the modem down will limit the bandwidth used and will decrease the room for error, however it will affect internet performance. The preferable solution is to update your modem drivers/firmware to the latest version.

Other possible causes of Lost-Carrier include:

  • A fax or older model T200 touch phone. Both of these devices draw voltage from the phone line and may cause a modem to disconnect. This is usually identified by regular disconnections every 10-20mins.
  • A home security system may poll the telephone line for security purposes at given intervals
  • Fluorescent lights, mobile phones, cordless phones and base stations all emit electromagnetic fields which may drop a connection.
  • Certain telephone switchboards may also interfere with modem signal.
  1. Disconnect all devices listed above that may cause interference.
  2. Disable call waiting on your phone (if you have it).
  3. Check the phone cord running between your computer and the wall jack. Make sure it is in good condition.
  4. Check the phone wall jack. Is the connection solid? Does it feel loose?
  5. Make sure the phone cord does not pass through any other devices. Fax machines, splitters, filters or surge protectors.
  6. Make sure the phone cord is not entwined around or bundled with other electrical cords. Power cords and monitor cables can cause interference.
  1. Try the Tune-up suggestions at: http://www.hevanet.com/tech/tuneup.html
  2. Try and determine your modem make and model. This can usually be found in the Modem Control Panel. Check the manufacturer's web site for any firmware updates.
  3. Call your telephone company and complain of noise on your line. Do not mention Internet trouble initially, as most phone companies do not make any guarantees on data calls. See if they can check your lines.