The smaller connector has been chosen "to make room for the earphone moving to the bottom," some Web blogs report.
Apple-watching Web sites have long expected the end of the 30-pin connector, which takes up a lot of valuable space in ever-smaller devices.
If the prediction is accurate, it means the new phone would not connect with current accessories such as speakers and power chargers that form part of the ecosystem around iPods, iPads and iPhones without some sort of adapter.
However, that could mean a sales boom for accessory manufacturers, Pete Cunningham, London-based analyst at technology research firm Canalys, told The Daily Telegraph.
"It represents an opportunity for accessory vendors," he said. "The iPhone connector has been a standard for a long time now and I would expect the same to be true for a new connector, should Apple change it as expected."
Some analysts say they expect Apple to offer a solution for people invested heavily in expensive speaker docks or other expensive iPhone accessories.
"Apple needs to find a solution not to disappoint their current clients who want to upgrade to the new iPhone but are tied to an expensive accessory they have bought," Franciso Jeronimo, an analyst at technology research firm IDC said.
"I believe Apple will come up with some sort of adaptor so the new iPhone can be used with previous connectors."
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