Sevice tax on export sevices

I have one  query. my friend offer software developments and such computer related services to foreign customers - where again the money is received into her Indian bank  account ((in foreign currency - converted to INR by the bank) through a payment gateway. 

Whether it is necessary to register under service tax?? 

is it exempt from service tax levy ??and if her earnings corss the 10-lac boundary?

Thanks for your guidance in advance.