Normally some brokerage companies involved in the STOCK TRADING and "brokerage "charged by them is the INCOME to them EG: INDIAINFOLINE , ICICI SECURITIES, INDIABULLS, HDFCSECURITIES,MOTILAL OSWAL ETC.,
Normally this type of firms employs , those who cleared the NCFM certification conducted by NATIONAL STOCK EXCHANGE(NSE)
Further more details please visit WWW.NSEINDIA.COM----->NCFM CERTIFICATON
I recomend , you should clear atleastte CAPITAL MARKET(DEALERS) and Derivatives MARKET(DELEARS)