关于没有outgoing call情况下的fxo占线情况的解决

shanlingyun

写了个tcl ivr，想不到在outgoing call leg建立的时候，对方不拿电话，我先挂掉，这样，ivr的outgoing call leg就断开了，但是ivr判读不了这问题。imcoming call leg一直保持在fxo口上，怎么办？？
保持在上面的incoming call leg 会使得fxo表现为忙，这样的情况下，fxo会一直忙音。真是烦人啊！
解决的方法很简单，当检测outgoing call leg断开的时候，系统延迟一个时间后就断开incoming call leg。我一直不明白cisco为什么不把这个检测功能做进tcl ivr，而是用一个命令来配。这个命令就是
guard-out         
英文说明是：a time window after call is disconnected that no outgoing call is allowed
下面是详细说明：
timing guard-out

To specify the guard-out duration of an Foreign Exchange Office (FXO) voice port, use the timing guard-out command in voice-port configuration mode. To reset to the default, use the no form of this command.
timing guard-out time
no timing guard-out
Syntax Description
time
Duration of the guard-out period, in milliseconds. Range is from 300 to 3000. The default is 2000.

Defaults
2000 milliseconds
Command Modes
Voice-port configuration
Command History
Release
Modification
11.3(1)MA
This command was introduced on Cisco MC3810.
12.0(7)XK
This command was implemented on Cisco 2600 series and Cisco 3600 series.
12.1(2)T
This command was integrated into Cisco IOS Release 12.1(2)T.

Usage Guidelines
This command applies to the Cisco 2600 and Cisco 3600 series routers and Cisco MC3810. This command is supported on FXO voice ports only.
Examples
The following example sets the timing guard-out duration on a Cisco MC3810 voice port to 1000 milliseconds:
voice-port 1/1
timing guard-out 1000

The following example sets the timing guard-out duration on a Cisco 2600 series or Cisco 3600 series voice port to 1000 milliseconds:
voice-port 1/0/0
timing guard-out 1000

但是：什么叫做guard-out ？
下面是cisco的解释：
Specifies the duration in milliseconds of the guard-out period that prevents this port from seizing a remote FXS port before the remote port detects a disconnect signal. The range is from 300 to 3000. The default is 2000.
这样，定义了timing guard-out 1000这个命令在fxo口上以后，fxo会1秒钟检查一次outgoing call leg的建立，如果发现没有outgoing call leg，它就关闭自己上的incoming call leg。


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