HMP Linux 4.1 update 165 rejects incoming INVITE with 486 Busy Here

Hi,

I have a problem on my SIP server :
Cent OS 6.6
Linux HMP update 165
120 SIP chanells

I receive incoming SIP calls and it all works fine until one moment.
Then on incoming INVITE HMP rejects call with 486 Busy Here and it doesn't inform my application about it.
I Know that this happens when there are no available Resources , but all of my channels were avilable as i can se that last 120 were distributed among all of those 120 channels and did get GCEV_DROPCALL and RELEASE_CALLEX from HMP:

Now i have no idea what is causing it.
Aftere i restart DIALOGIC and my application it works than again for a while and again i get the same problem
In dialogic rtf log i have no data about the call event thouh i added lot of debug in RTF config  file.