Breaking away from previous theoretical and empirical works on the consequences of upward voice, we theorize that an increase in the frequency of upward voice is more likely to alert managers’ attention to the voice and to project a competent image of the voicing employees to the managers. After the frequency of voicing passes an optimal point, a further increase in the frequency of voicing will however generate negative managers’ reactions. In Study 1, using time-lagged data collected from 219 supervisor-subordinate dyads, we found that, for employees with low rather than high LMXs with their managers, there was an inverted U-shaped relationship between the frequency of voicing, and managerial attention as well as their perceived credibility of the voicing employees. In Study 2, using time-lagged data collected from 131 supervisor-subordinate dyads, we found similar quadratic-by-linear interactive effect of prohibitive voice and LMX on managers’ attention, and on their evaluations of employees’ credibility, task performance, and promotability. Yet, our results show that the frequency of promotive voice was not related these outcomes.