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<concept xml:lang="en" id="GUID-D83D00F3-EF62-57F7-8FC6-549615C37710"><title>Telephony Watchers</title><shortdesc>This topic describes the telephony watcher classes and the information they provide to the client applications. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><p>The telephony watcher is the framework that contains the telephony watchers. The watchers are the DLLs and they monitor telephony related information such as signal strength, battery level and call states. The telephony watchers use <xref href="GUID-FE910347-7CC1-5241-B443-88AD3F5A96EF.dita">publish and subscribe</xref> to publish the information. The client applications must register with the watcher to receive the updates from the telephony system. </p> <p>The telephony watcher framework contains two watcher plug-ins: </p> <p><b>Signal strength watcher </b> </p> <p>The signal watcher notifies all registered client applications of the changes to the radio signal strength. </p> <p><b>Call indicator watcher </b> </p> <p>The call indicator watcher notifies all registered client applications of the call progress information of active voice, data and fax calls. </p> <p>The watcher classes get the state information from the multimode telephony API and publish the notification to the registered client applications. </p> </conbody></concept>