Grandstream GXP2000 message button not working

I have setup Asterisk@Home with Grandstream GXP2000.
Everything seems to be working (out bound call, inbound call, transfer, etc), escept that when I press message button trying to check voicemail, it says “The extension is busy”, while I am expecting it to ask me for password.

Does anyone encountered this problem before.
Your comment will be greatly appreciated.
Thanks,

  • Dickson

it would help if you told us what you have set your message button to send !!