Except as provided in §§ 12-3-102 and 12-3-103, all goods and services, and all telephone, telegraph, electric light, gas, power, postal services, and the leasing of any equipment required for the use of state government, shall be purchased and contracted for by the central procurement office consistent with the requirements of this chapter and any rules, regulations or policies and procedures approved by the procurement commission.
T.C.A. § 12-3-101