This can occur in both dial up transactions and TCP/IP transactions.
If dial up verify that no other program is using the modem. The most common programs are fax and shipping programs or PC Anywhere.
If TCP/IP, go to Setup/Modem (or Setup/Hardware Setup/Modem) and click on Use Simple Modem Setup in the bottom left-hand corner, then click OK (if the bottom left-hand corner says Use Manual Modem Setup, then the software is already configured in Simple Modem Setup). | 
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