Hi Alex
7745 & 7743 mostly comes along with 2993 because call failure rate will be too high for that TRX.
In Ultrasite BTS Hub Manager,check for TRX bypassing configuration & Cross connection.Also check for incorrect E1 TS bypassing.2993 never comes for any type of H/W fault,it comes only due to configuration mismatch between Site(BTS HUB Manager) & OMC configuration.
The supplementary info in 2993 alarm will tell you the culprit BTS, TRX & PCM on which it is configured