SAN FRANCISCO - Apple Inc will start a program this month to allow users to trade their older iPhones for the newest model, Bloomberg cited people familiar with the plan as saying, a first for the company as it prepares to introduce a new version of the smartphone.

It has teamed up with Brightstar Corp, a mobile phone distributor that runs similar trade-in programs for carriers like AT&T Inc and T-Mobile, to handle exchanges, Bloomberg cited the unidentified sources as saying on Thursday.

Apple and Brightstar did not immediately return calls for comment.

New iPhones with no wireless contract are priced starting at $649, depending on storage size. Demand is typically strong but investors worry that, as the US market becomes increasingly saturated, smartphone purchases will slow sharply.

A trade-in program can help bolster demand for expensive new models, especially as arch-rival Samsung Electronics Co Ltd steps up an aggressive push to sell its own devices in the US market.