John Stephens, AT&T senior executive vice president and chief financial officer, says the company is on track to break its single-quarter record for smartphone sales.

Speaking at the UBS 39th Annual Global Media and Communications Conference in New York, Stephens said that AT&T sold about six million smartphones in the first two months of the fourth quarter. Because December is traditionally one of the strongest sales months, AT&T now expects to break the previous single-quarter smartphone record of 6.1 million.

AT&T’s strong smartphone sales in part reflect a higher number of handset upgrades from customers who were waiting for the launch of a new iPhone. AT&T previously announced that it activated more than one million iPhone 4S’ in the first five days the device was available. AT&T said iPhone 4S sales remain strong.