[Asterisk-Users] Voicemail shorter then (ex) 2sec - don't accept

[Joseph]

In which configuration file I can specify that I don't want to accept
messages for example shorter then 2sec. ?
I've looked in voicemail.conf but I couldn't find any setting that will
support this option.  

In most cases message shorter then 2 or 3sec will not contain any
message and I don't want system to record them and sending an email to
me.

-- 
#Joseph