There is a problem with the DRUs (RBS2x16) that were released earlier by Ericsson. The symptom will start to either have very low output power thus having low traffic then high SDCCH drop and high TCH failure or suddenly will not carry any traffic at all. Ericsson is now replacing the DRUs with version R1 & R2 to R3 to correct this problem. They have also released a patch for the BSC to detect this problem and new BTS SW version to automatically block the faulty DRU. Temporary solution for this problem is to block trx or replace the DRU.