The department is responsible for:(1) the management of a system of telecommunications services, Texas Agency Network (TEX-AN) to meet all state agencies intercity and intracity telecommunications requirements to the extent possible and to the extent that funds appropriated are available for that purpose;(2) the provision of centralized telephone service for state agencies, each house of the legislature, and legislative agencies in the capitol complex telephone system (CCTS);(3) the acquisition of any or all of the facilities, telecommunications services and/or equipment necessary to provide telecommunications and CCTS services;(4) promulgation and dissemination of appropriate guidelines, and operating procedures, and publication of CCTS telephone directories to insure efficient operation of telecommunications and CCTS services;(5) operation of a system of billings and charges for services provided in operating and administering telecommunications and CCTS services; and(6) the provision of network security services to state agencies and other entities as provided by §2059.051, Government Code.