Exchange 2007 SP2+AudioCodes MP-114
刚开始调试的时候发现接通率非常低，百思不得其解。
后来叫了PBX供应商过来看，测了振铃电压，发现比较低。换板卡，提高振铃电压后一切正常。此时调试传真功能，发现传真不出现握手音，用户只能收到语音邮件，邮件内容就是滴滴滴滴……。郁闷之下狂搜索一番，找到如下文档：
 
其中比较有用的一段如下：
For fax receiving to work correctly with some IP PBXs, you may need to enable inband fax tone detection by changing the EnableInbandFaxDetection setting to True in the globcfg.xml file. The globcfg.xml file is located in the \Program Files\Microsoft\Exchange\bin folder on an Exchange 2007 computer that has the Unified Messaging server role installed. If you do not configure this setting, Unified Messaging servers must rely on IP gateways to perform inband fax tone detection.
 
把EnableInbandFaxDetection的值改为TRUE之后，一切正常。