X0306 4 2017-06-20 0001005757 CSG SYSTEMS INTERNATIONAL INC CSGS 0001514482 Hughes John L 9555 MAROON CIRCLE ENGLEWOOD CO 80112 1 Common Stock 2017-06-20 4 F 0 900 41.68 D 16798 D The vesting on 3,000 shares of restricted stock held by Mr. John L. M. Hughes was accelerated due to his death. The sold shares on this form represent those shares sold to cover a portion of the personal income tax withholding requirement as a result of such vesting. John L. M. Hughes 2017-06-22