Problems with voicemail notify

Good morning,

In my company we are having some problems with a client’s voicemail. Sometimes a person leaves a voice message, but the Asterisk doesn’t send requests to the phone for active the phone’s led, so the client doesn’t known that he have messages if he doesn’t consult the voicemail.

In the image you can be seen how the Asterik don’t send requests (0/23) while the client have messages:

root@*****:/var/spool/asterisk/voicemail/default/**********/INBOX# ls
msg0000.txt msg0000.wav