Deployment of intelligent transportation systems (ITS) in major cities of the United States and inauguration or upgrading of transportation management centers (TMCs) have enhanced the ability to better manage centers (TMCs) have enhanced the ability to better manage transportation networks. One of the main goals in design and operation of TMCs is the ability to detect incidents promptly and reliably. Several methods are implemented to achieve this goal, including methods relying on data collected by loop detectors or other technologies. Recent limited experiments suggest that wireless telephones can be an effective tool in incident detection. A probabilistic analysis approach is adopted here to analytically determine the effectiveness of this method for incident detection. This analysis indicates that wireless phone calls to emergency services (i.e., 911) can provide valuable and timely information for incident detection. Furthermore, adoption of the Federal Communications Commission (FCC) requirements for identifying and locating E911 callers would reduce the likelihood of receiving false alarms from wireless phone callers; hence, it would provide TMCs with an inexpensive, fast, and reliable source of information for incident detection and verification.