i want to learn the security issues related to PBX,telephone Exchange and telecomminications, scratch cards ,prepaid cards, satellite security from beginning to advance level probably from a hackers perspective. Is there any comprehensive material and sites avaible on internet, or any ebook avaible for download? i cant find any , there is just introduction , is there any thesis releted to it , please tell me urgent as i want to submit my reports in a week.
i have searched the sites like http://iroi.seu.edu.cn/books/ee_dic/whatis/pbx.htm
but there are papers mostly related to a particular company scenario or they just mentioned the security problem in a field , no types of attacks and how to avoid them nothing is there.
i will be thankful to you people if you help me in this regard immediately.