New Delhi, Jan 29 (IANS): The US' smartphone sales remained flat year-over-year (YoY) in the fourth quarter of 2021 as premium flagship devices were in short supply during the holiday season, says a new report.

According to Counterpoint Research, strong holiday promotions in carrier channels, backorders due to supply constraints, delayed launches and in-store restrictions due to Covid-19 remained key highlights of the quarter.

"The US smartphone market was very competitive in Q4 2021. Carriers were aggressive with promotions to retain their smartphone bases. This contributed to continued record or near-record low smartphone churn among the major carriers," Jeff Fieldhack, Research Director, said in a statement.

Apple sales grew 17 per cent quarter-on-quarter (QoQ) with demand for the iPhone 13 series outpacing supply, especially for the Pro series models.

The iPhone 13 Pro and Pro Max were on backorder much of December, with wait times lasting up to six weeks.

Samsung sales grew 11 per cent YoY. Several factors held back the brand's sales, including shortages of the Galaxy S21 series devices and the delayed launch of the Galaxy S21 Fan Edition.

But a higher mix of the A-series and strong performance of foldables helped Samsung register YoY growth, the report said.

Fieldhack noted that specific to hardware sales, T-Mobile was the largest smartphone channel in the US and grew modestly YoY. Verizon was the second largest smartphone channel and was flat YoY.

AT&T was the third largest channel and its smartphone volumes fell just over 4 per cent YoY.