Hello friends,
Let me tell something about RAC and LAC.
LAC (Location Area Code) is a unique code which is used for calling of the gathering of the tens or hundreds of Base Stations into a single BSC(Base Station Controller).
A subdivision of the LA is called RA(Routing Area) is used by the mobiles which are GPRS attached and the RAC(Routing Area Code) is the code for the calling and differing of various RAs.