There are a number of ways to monitor traffic and help people to navigate through or avoid traffic jams. A prospective way is to use smart phones with GPS enabled device as traffic sensors, which complement existing sensors. This paper attempts to highlight a number of progressive steps in the effort to build an integrated ITS, which harnesses smart phones as intelligent agent. However, a number of questions should be addressed first: How smart phones can avoid map mismatching phenomenon which is a common problem in navigation devices ? What if there are compromised agents which attempt to invalidate the gathered data ? and how to place detectors in such a system. Consequently, there are three possible solutions discussed in this paper: the use of non-overlapping zones in Virtual Detection Zone (VDZ), filtering algorithm to ignore compromised agents and the use of macroscopic simulation to aid the placement of VDZ in selected roads.