[Serusers] Problem with SER accounting, Please help

Hi All, I was able to install SER and able to get all the call details to the Mysql DB. But my problem is with the time of timestamp recorded, it is not recorded according to time on Server where my DB is located. The time recorded is according to timezone of the caller and so because of this when I use NOW() of Mysql and get the calls I miss the calls dialled from timezones ahead of NOW() time on Mysql. I think while inserting call details in to DB the acc.so module is using some other thing other than using NOW(). Please tell me where can I modify that query and get a common timezone for all the users so that billing will not be a problem for me. Any help will be sincerely appreciated. Thanks, Manoj.