47 CFR § 80.108 - Transmission of traffic lists by coast stations.
(a) Each coast station is authorized to transmit lists of call signs in alphabetical order of all mobile stations for which they have traffic on hand. These traffic lists will be transmitted on the station's normal working frequencies at intervals of:
(1) In the case of telegraphy, at least two hours and not more than four hours during the working hours of the coast station.
(2) In the case of radiotelephony, at least one hour and not more than four hours during the working hours of the coast station.
(b) The announcement must be as brief as possible and must not be repeated more than twice. Coast stations may announce on a calling frequency that they are about to transmit call lists on a specific working frequency.