SAN FRANCISCO -- Apple today began letting U.S. iPhone owners trade in their smartphones for credit toward buying new models.

The California company's trade-in program kicked off in the wake of unconfirmed reports of a September 10 event at which Apple will unveil new iPhones, with rumors ranging from a gold handset to a low-price version aimed at emerging markets.

"iPhones hold great value," Apple spokeswoman Amy Bessette said. "So Apple retail stores are launching a new program to assist customers who wish to bring in their previous-generation iPhone for reuse or recycling."

Bessette declined to specify how much Apple (IW 500/4) is paying for old iPhones, but they can fetch $300 or so depending on model at an array of websites or U.S. consumer electronics shops that buy handsets.

The Wall Street Journal earlier this month reported that Apple had asked its Taiwan-based supplier, Hon Hai Precision, to begin shipping two new versions of the iPhone in September, including a lower-cost model.

Speculation has centered around whether Apple will shift its strategy of focusing on premium devices priced at the high end of the market to include a lower-cost handset to appeal to people with tight budgets.

A survey by Gartner said Apple's share of the smartphone market worldwide fell to 14.2% in the second quarter, while Samsung's share rose to 31.7%.

Samsung has found global success with smartphones powered by Google's free Android software, which now dominates the market.

Copyright Agence France-Presse, 2013