help me guys plzzz

hi friends,
i am pursuing my M.S in networking and telecommunications. i am doing my internship with an MNC in 2 domains network security and VOIP. now i want to select only one field for career path.so please suggest me to which field i need to select and where i will get good growth in career.
thanks in advance

Though this is not one glove fit all, but I see you making more money in voice especially if you hang around the Cisco line. But interms of career growth, security is the way