MWI Notify Error on Audiocodes MP-124

Hi Guys,

I,m having problems configuring MWI on my Audiocodes MP-124 FXS. When my Asterisks send the “Notify” command to the Audiocodes, It responds with a 481 Call/Transaction Does Not Exist
I?m using Asterisk

Do you know what might be the problem?. I?m also using a Linksys PAP2 and is working fine.