It's commonly accepted that AT&T's iPhone exclusivity will end soon when Apple adds Verizon to its US carriers — but AT&T's chief exec isn't worried, citing the fact that his subs are trapped.

"If you look at the iPhone base, about 80 per cent is either on a family-talk plan or in a business relationship with us," CEO Randall Stephenson told a Goldman Sachs investors conference Tuesday, according to MarketWatch. "Those customers tend to be very sticky. They don't churn very frequently."

"Sticky," that is, meaning stuck in Big Phone's standard two-year iPhone contract, unable to jump ship to Verizon without paying a substantial penalty.

Stephenson may be speaking from considered experience, or he may merely be whistling in the wind to calm investors. Just this Monday, for example, no lesser light than Credit Suisse estimated that 1.4 million AT&T subscribers will switch to Verizon if — when? — the iPhone becomes available on the largest US wireless carrier's network.

But the survey upon which Credit Suisse's estimate was based did provide some backup to Stephenson's "We've got you where we want you" analysis: of the AT&T subscribers surveyed, 23 per cent would switch to Verizon if they could, but only 3 per cent would break their contracts to do so.

Advantage, Stephenson.

However, Credit Suisse's survey also showed that around 18 per cent of AT&T iPhone subscribers would take their business to Verizon once they were out of Stephenson's clutches.

And then there was the Morpace survey that found that 34 per cent of AT&T iPhone customers were waiting for the Jobsian handset to be offered by another carrier before upgrading.

Advantage, Verizon.

Still, the AT&T headman isn't worried. He sees plenty of growth in the wireless marketplace, both for "integrated devices" (read: smartphones) and other gadgets: "We are in the very early stages of this connected-device market," he told the conference.

All these numbers and opinions must wait until the Verizon iPhone becomes available to be tested. Although neither Apple nor Verizon have made any statements regarding the matter, a gaggle of rumors points to availability beginning in January 2011.

Wednesday, by the way, brought yet another rumor: according to AppleInsider, Apple will build 3 million Verizon-capable CDMA phones this December.

Stephenson is unarguably correct when he says that the market for "integrated devices" is growing. What is arguable, however, is how big a chunk of it will be left for him after those "sticky" subs get unstuck. ®