During the next 5 years, Federal, State, and local governments will spend an estimated $1.5 billion to $2 billion on interoperable wireless communications networks. Wireless networks allow for high-speed communications in places where infrastructure is nonexistent or has been destroyed. Some of the wireless technologies that have been impacting homeland security planning are enhanced 911 systems and sensor networks. The enhanced 911 systems include wireless location capability to aid in finding the precise location from which cell phone users are placing calls. Sensor networks enable the collection and monitoring of data on motion, sound, light, heat, and other environmental factors, such technology can be deployed to develop perimeter security systems around buildings. Other relevant wireless technology includes the Cargo Security Initiative which allows the U.S. Customs and Border Protection to collect cargo information before vessels pull into United States ports. Wireless technologies are also enhancing first responder access, providing advanced Internet service for mobile users, and aiding in disaster recovery efforts.