I have a pgw2200 set up with 3 ss7 interconnections and SIP trunk. Problem is that when SIP call is entering pgw and exiting via ss7 link there is a failure exactly 20 seconds after ACM message with temporary failure on ss7 side and 503 service unavailable on SIP side which is generated by pgw. Even when call is established failure still appears after 20 seconds from ACM message on ss7. And call gets disconnected. ss7 to ss7 works fine. Does anyone have any idea on this?