It turns out that as Americans, we're just not very loyal to our wireless carriers. In fact, we regularly cheat on them.

A new survey of the North American wireless industry by Pricewaterhouse Coopers has revealed that the average relationship between a wireless subscriber and his or her wireless carrier is at a new all-time low, Wall Street Cheat Sheet is reporting today.

Customers are switching carriers as soon as 48 months. Compare that with an average of 59 months in 2010. The survey found, however, that smaller cell phone companies are seeing the highest turnover, but the giants -- Verizon (News - Alert), AT&T and Sprint -- aren't keeping their customers for much longer.

“Competition is fierce and pricing is a key element,” said PwC's Pierre-Alain Sur. “That accelerates the jump from one carrier to another at the end of a contract period.”

Wireless carriers would appear to be engaged in an unwise vicious circle: the study has shown that customers are using fewer voice minutes, possibly to keep bills lower. This, in turn, causes carriers’ average revenue per smartphone to decrease. The wireless companies respond by seeking ways to increase revenue, which include increasing prices on phones and expanding margins.

Not very smart, but no one has ever accused the nation's largest wireless carriers of being overly smart when it comes to keeping customers.

Carrier subsidies for new smartphones are also pinching their pockets, according to the study. On average, carriers subsidize about $280 per smartphone. This shrinks their margins, particularly when the smartphone is a pricey one.

“A logical conclusion is that the Apple (News - Alert) iPhone is not good for wireless carriers,” says Mike McCormack, an analyst at Nomura Securities, told Wall Street Cheat Sheet. “When we look at the direct and indirect economics that Apple has managed to extract from the carriers, the carrier-level value destruction is quite evident.”