The TMU is the main control board of the BTS. The name of the main control board varies according to the BTS model.
For the BTS3012, BTS3012AE, BTS3006C, and BTS3002E, the main control board is the DTMU.
For the BTS3036, BTS3036A, DBS3036, BTS3900 GSM, BTS3900A GSM, and DBS3900 GSM, the main control board is the GTMU.