Called Party May Not Recognize Real-Time Communications Client Program Dialed Digits

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A real-time communications client program that uses in-band Dual Tone MultiFrequency (DTMF) with a G.723.1 codec may have trouble dialing recognizable digits because of poor tone quality.

The problem is more likely to occur during second stage dialing when you makes a computer to telephone call. This is typically required by called party Interactive Voice Response (IVR) units that prompt for digits, such as those used for prepaid calling cards, reservation services, and so on. A series of dialed digits that contain zeros (0) can be particularly vulnerable to distortion.
To resolve this problem, obtain the latest service pack for Windows XP. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
322389 How to Obtain the Latest Windows XP Service Pack

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

File information

The English version of this fix should have the following file attributes or later:
   Date         Time   Version      Size    File name   ---------------------------------------------------   03-Oct-2001  09:50  5.1.2600.15  829,440 Dxmrtp.dll				

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows XP Service Pack 1.
More information
DTMF is also known as "push button" or "touchtone" dialing.

Real-time communications client programs can accomplish audio and video calls as well as instant messaging.

The International Telecommunications Union (ITU) G.723.1 specification is a compression technology standard that is implemented in voice codecs for real-time video conferencing and telephony over standard phone lines.

In-band DTMF tones are sent as encoded audio signals, as opposed to out-of-band special DTMF Real-time Transport Protocol (RTP) packets (see Request for Comments 1889).

The following Request for Comments (RFCs) apply:
RFC 1889 RTP: A Transport Protocol for Real-Time Applications
RFC 2833 RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
For additional information about RFCs, click the article number below to view the article in the Microsoft Knowledge Base:
185262 How to Obtain Request for Comments Documents from the Internet
rtc coder-decoder im
Note This is a "FAST PUBLISH" article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. See Terms of Use for other considerations.

Article ID: 307527 - Last Review: 01/11/2015 21:02:22 - Revision: 1.0

Microsoft Windows XP Home Edition, Microsoft Windows XP Professional

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