asterisk users - May 2011 - obd call drops after few seconds : only for mobile numbers

Hi,

my obd calls to all Idea mobile numbers drops after few sec.
where as, with  same configuration , and making obd on to pri it works 
properly.
Also i had words with Idea team, they says release is from my point code, 
whereas on debugging at my asterisk server i received release from their 
point code.

using :- dahdi-tools-2.3 , libss7-1.0 , asterisk-1.6.2.

Any suggestions ...?