OC3/STM-1 Line Card

Hello Everyone, Anyone know of a way of bypassing the 90K audiocodes mediant 3000 equipped for STM-1 interface using line cards and a linux box :). What we are looking to do is replace our traditional ISDN DS3 equipped for voice using an STM-1/OC3 backbone and our own put together linux box. Again, this will be used for voice signaling... Kind Regards, Nick.