Public to private overflow from AVST

[alaint]

I'm having AVST connected to my OXE system thru VPS protocol over a T1 trunk.

I want to enable the private to public overflow from the Automated Attendant (AA)
so when the IP link is down between the Main area ( where we have AVST) and the remote site, if someone call from outside the AA, whilst in the AA, if the person select wthin the AA prompt to be transfered to and extension on a remote site ( currently rescued by a PCS) the AVST is not able to transfer the call ( just for the record, the private to prublic overflow is working, It means when the WAN is down between two sites, if you tries from site 1 to call an extension on site2, the system will translate internal number into external number and establish the call thru PRI )
The problem is that, somehow, the call coming from AVST -AA is not translated from internal to external when the link is down.
Any idea how to activate this?
Thank in advance.