AT&T has just released its financial report for Q1 2013, announcing an addition of 296,000 postpaid customers during the quarter. The carrier also says it amassed 1.2 million new smartphone subscribers, leading to its best-ever first quarter of smartphone sales. 6 million left shelves in all, with the iPhone enjoying a majority of those sales at 4.8 million. 72 percent (approximately 48.3 million) of on-contract AT&T customers are now carrying smartphones. In all, wireless revenues came in at $16.7 billion — up 3.4 percent over the same period last year.

Of the 6 million smartphones that left shelves, 4.8 million were iPhones

The carrier's move to shared data is also progressing smoothly. 14 percent of customers have moved over to the Mobile Share plans, totaling 10 million "connections" by AT&T's count. Interestingly, over a quarter of those accounts have opted to go with a data plan containing 10 gigabytes of data or more. The convenience of having every device on one bill seems to be drawing users away from their grandfathered unlimited plans, as well; over 15 percent of Mobile Share adds came from people giving up unlimited data.

AT&T's primary competitor, Verizon Wireless, announced last week that it had added 677,000 new subscribers in the quarter and sold 7.2 million smartphones, 4 million of which were the iPhone.

AT&T will be holding a conference call this afternoon to discuss the details of its financial report. We'll be tuned and will update this post with anything interesting that comes out of it.