33 CFR §161.21

1. (a)Unless otherwise directed, vessels equipped with an Automatic Identification System (AIS) are required to make continuous, all stations, AIS broadcasts, in lieu of voice Position Reports, to those Centers denoted in Table 161.12(c) of this part.
2. (b)Should an AIS become non-operational, while or prior to navigating a VMRS area, it should be restored to operating condition as soon as possible, and, until restored a vessel must:
   1. (1)Notify the Center;
   2. (2)Make voice radio Position Reports at designated reporting points as required by § 161.20(b) of this part; and
   3. (3)Make any other reports as directed by the Center.