多方通话中，禁止被叫方使用DYNAMIC_FEATURES中定义的功能（features）

场景：

8007发启了一个会议，会议室已经创建好，允许8007通过通过DYNAMIC_FEATURES中的按键来将被叫方加入到会议室，被叫不允许使用DYNAMIC_FEATURES中定义的按键功能。

我写的拨号脚本如下：

[dynamic-nway-start]
exten => _X.,1,NoOp(dynamic-nway-start)
exten => _X.,n,Set(CONFNO=9999)
exten => _X.,n,Set(MEETME_EXIT_CONTEXT=dynamic-nway-invite)
exten => _X.,n,MeetMe(${CONFNO},pdMX)


[dynamic-nway-invite]
exten => *,1,NoOp(dynamic-nway-invite)
exten => *,n,Read(DEST,dial,,i)
exten => *,n,Set(DYNAMIC_FEATURES=threeway-inv#threeway-noinv)
exten => *,n,Dial(Local/${DEST}@dynamic-nway-invite-dest,,g)
exten => *,n,Set(MEETME_EXIT_CONTEXT=dynamic-nway-invite)
exten => *,n,Set(DYNAMIC_FEATURES=)
exten => *,n,MeetMe(9999,pdMX1)

[dynamic-nway-invite-dest]
exten => _X.,1,NoOp(dynamic-nway-invite-dest)
exten => _X.,n,Set(DYNAMIC_FEATURES=)
exten => _X.,n,Dial(SIP/${EXTEN},,M(nway-join,9999,1))

[macro-nway-join]
exten => s,1,NoOp(dynamic-nway-join)
exten => s,n,Set(DYNAMIC_FEATURES=)
;exten => s,n,ChannelRedirect(${BRIDGEPEER},dynamic-threeway,9999)

我想在拨号脚本中通过 Set(DYNAMIC_FEATURES=)来取消被叫使用DYNAMIC_FEATURES中定义的按键功能。尝试了下，发现行不通，设置没有任何效果，被叫依然可以使用DYNAMIC_FEATURES中设置的按键。

解决方法：

仔细研究了下DYNAMIC_FEATURES，其格式定义说明如下：

; The syntax for declaring a dynamic feature is any of the following:
;
;<FeatureName> => <DTMF_sequence>,<ActivateOn>[/<ActivatedBy>],<Application>[,<AppArguments>[,MOH_Class]]
;<FeatureName> => <DTMF_sequence>,<ActivateOn>[/<ActivatedBy>],<Application>[,"<AppArguments>"[,MOH_Class]]
;<FeatureName> => <DTMF_sequence>,<ActivateOn>[/<ActivatedBy>],<Application>([<AppArguments>])[,MOH_Class]

;  FeatureName   -> This is the name of the feature used when setting the
;                   DYNAMIC_FEATURES variable to enable usage of this feature.
;  DTMF_sequence -> This is the key sequence used to activate this feature.
;  ActivateOn    -> This is the channel of the call that the application will be executed
;                   on. Valid values are "self" and "peer". "self" means run the
;                   application on the same channel that activated the feature. "peer"
;                   means run the application on the opposite channel from the one that
;                   has activated the feature.
;  ActivatedBy   -> This is which channel is allowed to activate this feature. Valid
;                   values are "caller", "callee", and "both". "both" is the default.
;                   The "caller" is the channel that executed the Dial application, while
;                   the "callee" is the channel called by the Dial application.
;  Application   -> This is the application to execute.
;  AppArguments  -> These are the arguments to be passed into the application.  If you need
;                   commas in your arguments, you should use either the second or third
;                   syntax, above.
;  MOH_Class     -> This is the music on hold class to play while the idle
;                   channel waits for the feature to complete. If left blank,
;                   no music will be played.

在格式定义说明中，我看到了ActivatedBy这个写法可以解决我这个问题，尝试了一把，问题解决了，applicationmap定义如下：

threeway-start => *0,callee/caller,Macro,threeway-start
threeway-inv => **,caller/caller,Macro,threeway-ok
threeway-noinv => *#,callee/caller,Macro,threeway-notok