33 C.F.R. § 101.310 – Additional communication devices.

(a) Alert Systems. Alert systems, such as the ship security alert system required in SOLAS Chapter XI-2, Regulation 6 (Incorporated by reference, see § 101.115), may be used to augment communication and may be one of the communication methods listed in a vessel or facility security plan under part 104, 105, or 106 of this subchapter.
(b) Automated Identification Systems (AIS). AIS may be used to augment communication, and may be one of the communication methods listed in a vessel security plan under part 104 of this subchapter. See 33 CFR part 164 for additional information on AIS device requirements.