cenvat credit on mobile bill in service tax

 we are one of the sotware develpment,we are updates software every year in our client office total receipt are adouve rs 8 laks whether cenvat credit is available on mobile bills  under service tax 

whether any cenvat credit not taken in the perticular period.are available to the naxt quarter/next period

pl clerify and if any notification or circular is available or not