Asterisk cmd voicemail

记录下asterisk拨号方案中 VoiceMail参数：

Records the channel, saving an audio file in a given voicemail boxnumber,
which must be configured in voicemail.conf.
The boxnumber may
be preceeded by one or more flags or
these may be specified as the second argument:

s: The letter s, if present, causes the instructions ("Please leave your message after the tone. When done,
hang up, or press the pound key.") to be skipped.

u: The letter u, if present, causes the unavailable message to be played. By default, the message says, "The
person at extension ... 1234 ... is unavailable," but the mailbox owner may record their own unavailable message with the VoicemailMain command.

b: The letter b, if present, causes the busy message to be played. By default, the message says, "The person
at extension ... 1234 ... is busy."

g(#): (Only when specifying the flags as the second argument) Adjust the gain of the recording. The # is an integer representing the amount of gain
in decibels. (This actually sets a channel option to increase the RX gain, this option is unfortunately only supported on Zap, see the volgain voicemail.conf option to have asterisk call sox to adjust the gain on voicemails sent as email attachements)

You may not specify both u and b flags
together. You may, however, combine them with s,
giving six possibiities:
s: Play nothing.   什么都不播放
(no flags): Play instructions. 没有参数的时候只播放留言提示“请在bi后留言”
su: Play unavailable message. 拨方无效消息
u: Play unavailable message, then instructions. 播放无效消息 并播放转接留言提示
sb: Play busy message.  播放忙的消息提示
b: Play busy message, then instructions.播放忙的消息，并播放转接留言提示