S.C. Code Regs. § § 117-329.1
Communications are subject to sales and use taxes pursuant to Code Sections 12-36-910(B)(3) and 12-36-1310(B)(3), which impose the tax on the "gross proceeds accruing or proceeding from the charges for the ways or means for the transmission of the voice or messages, including the charges for use of equipment furnished by the seller or supplier of the ways or means for the transmission of the voice or messages."
"Charges for the ways or means for the transmission of the voice or messages" is defined to include, but is not limited to, charges for access to, or use of, a communication system (the manner, method or instruments for sending or receiving a signal of the voice or of messages), whether this charge is based on a fee per a specific time period or per transmission or any other method.
S.C. Code Regs. § 117-329.1