• You are dialing the wrong number
• There is a problem at your ISP or in the telephone network
• You have voice-mail or other custom calling feature that produces a stutter dial-tone
• You haven't specified the proper country settings for your modem and the number you are dialing, or your modem doesn't support the country you are in.
• If you include the disable call waiting code in your dialing, and your phone line does not support call waiting; or, if you have call waiting, but your phone company doesn't support the disable call waiting code.

Check the settings for the DUNS Connectoid you are using.

If you have voice-mail or other custom-calling feature that produces stuttered dial-tone, you may be able to eliminate the problem by disabling dial-tone or busy detection: Add x to extra settings to disable busy and dial-tone detection; add x2 to extra settings to disable only busy detection.

If your modem doesn't offer support for your country, disabling dial-tone/busy detection (x in extra settings) might work (only if tone or pulse dialing for selected country is compatible with yours).

Use modem's speaker to listen to connection attempt: Make sure it dials, and make sure you do not hear a busy signal. 

Examine Modemlog to see what number is actually being dialed. (If # dialed is not displayed, adding E1 to extra settings may help.)

Try dialing with pulse instead of tone; Try increasing the tone duration. [ s11=120 ]