Check the following:
To the DTAU: Check for 4*5 TBM cards by issuing DTBM.
If all TBM cards are 4*5, verify GAIN is ON by issuing: DAMP.
If GAIN is OFF. Issue: SAMP ON.
In DRTU/BRTU verify or change the TAP TYPE to DTAU2 by issuing ED-DB-TAP::<tapid>:CTAG::TYPE=DTAU2;