1.7725 alarm comes when in response to channel activation command from BSC to BTS,the BTS replies with a channel NACK & you get this alarm in BSC.
2.The supplementary info will tell you is it for a TCH or a PDTCH or a DTM TCH
3.If it is for both check for soft channel capacity in BSCU’s,may be it is overloaded.
4.If it is for PDTCH only,check for overloading of PCU,in this case try reducing the CDED & CDEF(do not increase it by any means) or Load balancing of PCU’s.
5.If all the above cases are false & 7725 is for PDTCH only,check for PCU abis syncronisation logs.
Let me know which of the above cases are true for you?
If you are using DTM,let me know as then you will have to check for some more things