CSG Systems International, Inc. provided earnings guidance for the full year 2021. For the period, the company expected GAAP revenue to be in the range of $1,015,000,000 to $1,045,000,000, GAAP operating income to be in the range of $125,200,000 to $133,000,000 and GAAP net income to be in the range of $75,200,000 or $2.35 per share to $80,900,000 or $2.53 per share.