Despite increased competition from its rivals to carry and sell Apple’s latest iPhone handsets, AT&T customers have remained loyal to the operator, resulting in almost no increase in customer churn, Glen Lurie, AT&T’s president of emerging devices has revealed.

AT&T lost its 4-year exclusivity on the iPhone when Apple opened up sales of its iPhone 4 smartphone to Verizon customers in February 2010. However, customers have chosen to remain with the operator despite additional operators offering Apple handsets.

“Churn has not moved at all,” said Lurie, adding that since the iPhone 4S was released, it has seen record-breaking sales of the new handset which has led to supply issues with customers now experiencing a one or two week wait to get their hands on the iPhone 4S.

AT&T announced during its third-quarter financial call that the company had activated over 1 million iPhone 4S handsets, totalling 2.7 million iPhone activations in that period – a decline from 3.6 million in its third quarter.

The AT&T executive also said that the company has an increase in adoption in the enterprise over the past three years as I.T departments and ‘chief information officers’ have begun to warm to Apple’s iOS platform.

Although Apple has been good to the company, Lurie warned investors not to discount smartphones from other mobile vendors, including Nokia and RIM, adding that AT&T needs them to ensure it remains competitive and is able to innovate.