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How to set the number of rings for RAS Auto-Answer in Windows Server 2003, in Windows XP Professional, in Windows Server 2000, and in Windows NT 4.0

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In Microsoft Windows NT version 4.0, the Remote Access Service (RAS) answers incoming calls on the first ring. In Microsoft Windows 2000, in Microsoft Windows XP, and in Microsoft Windows Server 2003, the Routing and Remote Access Service (RRAS) answers incoming calls after the second ring. The documentation in the Remote Access Administrators Help file describes how you can modify the RAS Modem.inf file to change this behavior. However, this only works if RAS is not using any Telephony Application Programming Interface (TAPI)/Unimodem-based devices.

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Beginning in Windows NT 4.0, RAS and RRAS are capable of using TAPI. It also maintains backwards compatibility with Windows NT 3.51. However, RAS and RRAS are not capable of using both TAPI and the Windows NT 3.51 Modem.inf information. If RAS or RRAS is using TAPI, then modifying the Modem.inf file to change the number of rings to wait before answering has no effect.

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WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

In Windows, to set the number of ring messages from the modem after which RAS or RRAS will answer the call, add the following key to the Registry if it does not exist:
Then, add the following REG_DWORD value to this key:
This REG_DWORD registry value can be in the range of 0 to 20. If a 0 value is used, the system does not watch for rings (available since Windows NT 4.0 Service Pack 5). If this value does not exist, or is outside of this range, the default value of 1 is used. If RAS is not using TAPI, this value is ignored and the documentation about modifying the Modem.inf file is correct.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
221308 NumberOfRings=0 does not work for RRAS auto-answer in WinNT4.0

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Keywords: KB145879, kbhowto

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Article Info
Article ID : 145879
Revision : 7
Created on : 2/21/2007
Published on : 2/21/2007
Exists online : False
Views : 159