-spec handle_call([], From, state()) -> {stop, normal, state()} when From :: gen_server:from().

-spec handle_cast(term(), state()) -> {noreply, state()}.

-spec init(Id) -> {ok, state()} when Id :: id().

-spec new() -> {ok, Id, CallGatekeeperCode} when Id :: id(), CallGatekeeperCode :: binary().