i want to add new attributs

Hello All, I m Harish Gupta from india, i m working in a Telecom & ISP company as system Administator and I m using freeradius application on linux platform(CentOS4.0) for my dialup users . its working fine, but i want to add a new attribute like "caller-id and calling-id " how can add these attributs plz. help me . Thanx & Regards Harish Gupta System Aministrator India +919828032258