Distinctive Ring and Modems

DISTINCTIVE RING and Windows XP & 2000 (24-Feb-05)

Microsoft removed distinctive ring support from Windows 2000 & XP! The Unimodem5 driver included with these versions of Windows does not support distinctive ring. Application software using TAPI does not receive any distinctive ring information provided by your modem.

TAPI - Microsoft Windows provides a Telephony Application Program Interface that is supposed to allow software developers to write applications without having to build support in for any particular hardware. TAPI supports distinctive ring.

UNIMODEM - Microsoft provides a "Unimodem" driver (service provider) that provides the connection between your modem driver and TAPI. It is this Microsoft Unimodem driver that does not provide support for your modem's distinctive ring reporting that prevents TAPI-compliant applications from working.

Microsoft offers 2 resolutions for people who want to use distinctive ring features:

Use Windows 98SE or Me

Obtain and install a third-party device to provide support for distinctive ring feature.

What does this mean? If you don't want to step back to old Windows, you would have to find a replacement for the Windows Unimodem driver in order to provide support for TAPI-compliant software - and I don't know of any. Another solution is software that bypasses TAPI and deals directly with the modem. (This is a step backwards in the way Windows works.... ) For Windows 2000 & XP - if you want distinctive ring support, you'll need software that is written to provide support for your modem chipset - TAPI-compliant isn't enough. And, of course, you'll need a modem that supports distinctive ring.

Another solution: I'm told that there's a trick to make distinctive ring work even under Windows 2000 & XP and that it's implemented in at least one piece of faxmodem/TAPI-compliant software: VentaFax & Voice ($34.95 personal edition - has 30-day free trial). This software has a special option in its settings that allows the modem data to be captured and analyzed after TAPI reports the first ring --- this means that the distinctive ring is distinguished only on the 2nd ring so the limitation here is that if auto-answer is set for the first ring, no distinctive ring information is obtained. However, if auto answer is set to second or higher ring, the software will get distinctive ring data.

Partial Distinctive Ring Support is possible if you want the modem to answer only on a particular distinctive ring by modifying the registry or the modem's .inf file. This is accomplished by changing the appropriate responses in the registry. This can be done by editing the registry with regedit.exe, or by editing the modem .inf file and re-installing the modem, which will modify the registry entries.

Your modem .inf file will be identified in the modemlog. The .inf file is located in the \windows\inf folder. (This folder may be hidden - you can unhide it in Explorer, menu item Tools, Folder Options..., View Tab, and select show hidden files and folders.) Make a backup copy of the original .inf file, then open it with Notepad. Search for RING<. You'll see an entry similar to the following (USR modems - see note at bottom of this page):

HKR, Responses, "RING<cr><lf>", 1, 08, 00, 00,00,00,00, 00,00,00,00

Note the 08 - the 08 is the code that tells TAPI to answer the call.

The .inf file will also contain responses with the distinctive ring strings returned by your modem - RING1, RING2, RING3, or RING A, RING B, RING C, or DRON= DROF= depending upon your chipset similar to following:

HKR, Responses, "<cr><lf>RING1<cr><lf>", 1, 18, 00, 00,00,00,00, 00,00,00,00 (Supra)
HKR, Responses,"RING A<cr><lf>",1,18,00,00,00,00,00,00,00,00,00   (USR)

HKR, Responses, "DRON=", 1, 91, 00, 00,00,00,00, 00,00,00,00    (Lucent/Agere)
HKR, Responses, "DROF=", 1, 92, 00, 00,00,00,00, 00,00,00,00    (Lucent/Agere)

For modems not using DRON=/DROF=, simply change the 18 code on the ring pattern you want the modem to answer on to 08, and change the RING<cr><lf> line's code to 18. Save the .inf file, uninstall and re-install the modem. The registry will be updated with these entries. Enable distinctive ring on your modem with appropriate initialization string (this may vary from modem to modem), and the modem will then answer on the selected ring pattern and will not answer on the RING response. (You can enable distinctive ring via the modem's extra initialization settings - the initialization string to enable distinctive ring can be found by searching the .inf file for EnableDistinctiveRing), or by modifying the default initialization string. To do the latter, search the .inf file for Init,2 and add the distinctive ring string to the string in quotes.

For modem using DRON=/DROF= (Lucent/Agere), you'll need to identify a unique DRON=## (and possibly DROF=##) pattern and code it into the .inf file. You'll remove the DRON= and DROF= entries in the .inf file, replacing it with the appropriate DRON=# [DROF=#]... string with the 08 parameter.

(When a modem is installed, the .inf file controls what registry entries are made. You can also accomplish the above by editing the registry directly locating the appropriate keys in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Unimodem\DeviceSpecific\(...your modem name)\Responses ).

Also note that your .inf file may have separate sections for VOICE and DATA, as well as separate initialization options for voice and data, allowing you to change the appropriate sections to control initialization and answering for both voice and data modes.

USR Modems: ATS41=1 enables distinctive ring on USR V.92 modem.
You may need to set the response string value for rings you do not want the modem to answer on to 00 in addition to setting the response string to 08 for the ring you do want the modem to answer on.

DISTINCTIVE RING and Windows XP & 2000 (24-Feb-05)