[Users] Hung up problem

Hi Users,,,, small issues in openser.. UAC 1 , UAC 2 are behind the NAT.. UAC 3 in NAT When I Make call UAC 2 <=================> UAC 1 , After 32 second its automatically hung up the Softphone. Same like .......... whe n UAC 1 <====================================> UAC 2 . When stranger interesting to all Users in OPENSER Developers in this world.. UAC 3 <============================> UAC 1 . it doesn't Hung up the phone But voice is not Hearing .. and UAC 1 <======================> UAC 3 its Hung up automatically ..... voice is clear... listening .. Where will be the problem either in softphone ( x-lite 3,0) or openser.cfgnat .... I thing the TM parameters is holding the Time . to process the call ... please help me................ -- Thanks and Regards with cheers Sunkara Ravi Prakash (Voip Developer) Hyperion Technology www.hyperion-tech.com