In addition to our combination of debt financing for the TARGUSinfo acquisition and share repurchases we have created, an intent to sustain a more efficient capital structure. In the first quarter of 2012, NeuStar demonstrated both the soundness of the strategy we have chosen and our ability to execute on that strategy. We've delivered on our top line growth with revenue increasing by $53.5 million year-over-year.
All 3 operating segments contributed to our revenue growth in the quarter. Our Information Services operating segment, that is TARGUSinfo, contributed $35.7 million. Carrier Services revenue grew by $14.8 million, driven by the annual growth escalators and the exploration of the incentive credits related to our NPAC contract. The revenue growth of $3 million in Enterprise Services was driven by an increase in the number of Common Short Codes and domain names under management, as well as expansion of our solutions within Internet Infrastructure Services.
We've also maintained the healthy margins that our shareholders expect with an adjusted net income margin of 22%. From a capital structure and capital allocation perspective, we have resumed the 3-year, $300-million share repurchase program originally announced in July 2010. The remaining authorized amount under the share repurchase program was approximately $185 million at the time of relaunch on March 14.
Since that date, we've repurchased an additional 655,000 shares for $23.8 million through quarter end. 2012 is once again a pivotal year for NeuStar with significant, challenges and opportunities and it's always my intention to be clear about our priorities and then to report on our fulfillment of them. I'd like to address the 4 areas on which we are most focused this year.Read the rest of this transcript for free on seekingalpha.com