Steven Campbell
Analyst · Raymond James Financial
Thank you, Ken, and good morning, everyone. U.S. Cellular's results reflect the continuing challenges of an extremely competitive market and a sluggish economy, in which all carriers continue to fight for a dwindling pool of new subscribers, and the cost of acquiring switchers are significant. On a positive note, as shown on Slide 8, fourth quarter retail gross additions were 298,000, up from 292,000 in the prior year quarter, and up from 284,000 in the third quarter. These results are evidence of our progress and increasing awareness with consumers and improving our sales execution.
With respect to net additions, in the postpaid segment, there was a net loss of 20,000 customers, as the increase in gross additions was offset by an increase in churn. However, as Mary Dillon will discuss in her comments, we did have positive postpaid net additions in December, the most competitive selling season of the year.
In the prepaid segment, we had an increase of 7,000 customers. So in total, we lost 13,000 retail customers in the fourth quarter of this year, compared to a net loss of 21,000 last year.
Our churn results are shown on Slide 9. Postpaid churn increased to 1.63% from 1.52% last year, which we attribute primarily to the launch of the new iPhone, the first new version introduced in the fourth quarter and across 3 national carriers, spanning a broader portion of our footprint.
We continue to add customers to our Belief Plans, in fact, 354,000 more during the fourth quarter, as they recognize the value and exceptional service that we provide. We currently have 3.1 million customers on our Belief Plans, which is critical to controlling and reducing churn, as customers on our Belief Plans who are out of contract, have significantly lower churn rates than legacy customers who are out of contract.
Slide 10 reflects our smartphone sales, penetration growth and postpaid ARPU. During the fourth quarter, we sold 505,000 smartphones, which represented over 52% of total devices sold. This compares to the fourth quarter of 2010, when we sold 395,000 smartphones or about 40% of the total units sold. Smartphones now represent over 30% of our postpaid subscriber base, compared to about 17% at the end of 2010. Although the overall cost to subsidize these devices is greater, the average revenue per customer also is higher, and we expect that will continue to benefit our results over time.
In fact, as you can see in the graph at the far right, postpaid ARPU has steadily increased over the past several quarters, driven by strong smartphone sales beginning late in the fourth quarter of last year, as well as by the continued migration of customers to the higher ARPU Belief Plans. This trend has more than offset the effects of the overall competitive environment and a significant downward pressure on voice pricing over the past several quarters. Postpaid ARPU was up 5% year-over-year to $53.35, up from $50.99 a year ago.
Also, remember that as part of the required accounting for the Belief Plans, U.S. Cellular defers a portion of its revenues to properly account for the loyalty reward program. In the fourth quarter, the company deferred $11.7 million in net service revenue, which had it been recognized as service revenue during the quarter, would have added another $0.73 to postpaid ARPU. That deferred revenue will be recognized in the future as either service or equipment revenues as the loyalty points are redeemed or used.
So turning now to our financial performance, which is shown on Slide 11. Service revenues for the quarter were $1,030,000,000, which is an overall increase of $38 million or 4% from last year. And breaking that down a bit further, retail service revenues were $882 million, an increase of $17 million or 2%. Inbound roaming revenues increased once again, growing $26 million or 38% year-over-year to $93 million, primarily as a result of increased data roaming traffic. We expect to see continued but more modest growth in this very high-margin revenue stream.
System operations expenses of $242 million were up $26 million or 12% year-over-year. This was due primarily to higher usage and roaming expenses as our customers used more data services, both on and off our networks. Through December of this year, total data network usage increased almost 3.5x over the same period last year.
Net loss on equipment for the quarter was $156 million, down $3 million from last year, primarily as a result of fewer total equipment transactions. The average loss per device sold was flat year-over-year despite the shift in mix to smartphones. In fact, given the 28% increase in smartphones sold and their greater share of the overall mix, we believe that we've done a very good job of controlling our equipment costs by better balancing the types of devices offered and our promotions on them and introducing lower-cost, entry-level smartphones to broaden our lineup.
SG&A expenses of $470 million were down slightly year-over-year. Reductions in advertising and improvement in bad debt expense were offset by increases in other selling and G&A expenses, due primarily to higher spending for phone exchange and loaner programs.
Operating cash flow for the quarter, $162 million, was up 15% compared to last year's $141 million, and operating cash flow margin was 15.7% in the quarter compared to 14 -- 14.3% last year.
Moving on to Slide 12. Below the operating income line, total investment and other income net for the quarter totaled $2.9 million, including earnings of approximately $12 million related to our interest in the Los Angeles partnership. Net income attributable to U.S. Cellular shareholders totaled $2.8 million or $0.03 per diluted share, versus $7.8 million or $0.09 per share in 2010.
The tax rate for the fourth quarter this year was 58.9%, compared to a tax benefit of 91.6% last year. As Ken already mentioned, the company recorded an adjustment in the fourth quarter to correct its deferred tax balances related to partnership investments that increased income tax expense by $6.1 million in the quarter. Last year, income tax expense was reduced by favorable settlements of certain state income tax audits.
And for the full year 2011, free cash flow was $216 million, net of cash used for additions to property, plant and equipment of $772 million, which increased $199 million or 34% over 2010. That higher spending reflects significant investments to deploy 4G LTE and for major initiatives such as our new billing and operational support system.
U.S. Cellular's balance sheet remains sound, and we have significant liquidity and financial flexibility together with an expected cash flow from operations and funds available under our revolving credit facility to meet our financing needs. At December 31, cash and short-term investments totaled $551 million, and we have about $300 million of unused borrowing capacity under our revolving credit agreement.
So now let me turn the call over to Mary Dillon. Mary?