Section 117.24 - Radiotelephone installation identification(a) The Coast Guard authorizes, and the District Commander may require the installation of a sign on drawbridges, on the upstream and downstream sides, indicating that the bridge is equipped with and operates a VHF radiotelephone in accordance with § 117.23 .(b) The sign shall give notice of the radiotelephone and its calling and working channels- (1) In plain language; or(2) By a sign consisting of the outline of a telephone handset with the long axis placed horizontally and a vertical three-legged lightning slash superimposed over the handset. The slash shall be as long vertically as the handset is wide horizontally and normally not less than 27 inches and no more than 36 inches long. The preferred calling channel should be shown in the lower left quadrant and the preferred working channel should be shown in the lower right quadrant.CGD 84-022, 51 FR 16308, May 2, 1986 It is recommended that the radiotelephone sign be similar in design to the Service Signs established by the Federal Highway Administration (FHWA) in U.S. Road Symbol Signs using Reflective Blue and Reflective White colors. Color and design information is available from the District Commander of the Coast Guard District in which the bridge is located.