The Branch of Communication Technology (BCT) manages the Service Wide Area Network (SWAN), enterprise technology engineering, Enterprise Messaging services including Personal Digital Assistant (PDA) support, directory and Web services, Land Mobile Radio, telecommunications, and national operational support through its Enterprise Technical Service Center (TSC) in Denver, Colorado. The SWAN is the communications backbone for the Service that provides mission essential connectivity to the Service's national e-mail system, the Internet, Web services, and many national software applications. The BCT Engineering and Operations groups work with regions and programs to research, test, and implement new technologies, solve network connectivity problems, and implement new circuits/nodes. The Service´s national e-mail system supports more than 9,000 users. Land Mobile Radio management involves designing radio facilities, assisting in the acquisition of radio systems and components and assisting in the installation of systems at Service offices throughout the country. Telecommunications support includes the ordering of voice and data services, billing and payment management, monitoring/recovery, coordinating with service providers and other agencies on voice circuit problems and changes, and assisting in the acquisition of telephone systems and services by Regions and field offices. The TSC provides support for Active Directory, national Web services, network applications, and network appliances for the SWAN and Service programs. This Branch represents the Service on several Department of the Interior (DOI) teams including networking, messaging and radio management.