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[ The PC Guide | Troubleshooting and Repair Guide | The Troubleshooting Expert | Troubleshooting Specific Components | Troubleshooting Modems | Call Waiting Problems ]

I have call waiting on my line, and I need to use my modem but incoming calls are interrupting and terminating my connections

Explanation: You have only one phone line in use for both voice and data calls. You want to be able to use your phone line for your modem without having incoming calls on call waiting interrupt the connection, possibly terminating it.

Diagnosis: When a call comes through on call waiting, an audible beep is generated that indicates the incoming call. To the modem, this is just an interruption of the signal, not a useful indicator tone. Many modems, especially older and cheaper ones, become confused by this tone and will drop the connection as a result, although newer modems are generally much better at tolerating this sort of disruption and carrying on (when a modem does this, you will experience a pause of a few seconds as the modem recovers from the interruption, but the call will continue.)


  • If you are using the phone for your modem a great deal, consider getting a second phone line. I have one and I couldn't live without it. :^)
  • Temporarily disable call waiting before you make your modem call. All (virtually all?) phone companies provide a special code that you can dial to disable call waiting during the next call you make on the phone. This is usually "*70" for a touch-tone phone, or "1170" for a dial (pulse) phone, but you should check to see what your phone company uses. To use this in a modem dial string, simply insert it with a comma before the number you want to dial. So instead of "ATDT5551212", you'd do "ATDT*70,5551212". The comma is a slight pause to allow for the split-second it takes the phone company to recognize the "*70" and return with the dial tone for the call.
  • You can permanently disabled call waiting on your phone line as well, of course, but this has other implications for how you want to use your phone service.
  • If your modem has a setting to control how long it can tolerate an interruption without dropping the call, try increasing it. Some modems will have this setting while others will not, and you will likely have to consult your documentation.
  • Replace your modem with one that is more tolerant of call-waiting interruption. In particular, newer modems with error detection capabilities will not be affected nearly as much by a call waiting disruption as an older modem without these features will be.

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