Apple Inc. (NASDAQ:AAPL) is expected to hold an iPhone upgrade event this week at the company’s retail stores in the U.S. to boost handset sales ahead of the launch of the next-generation iPhone, dubbed the iPhone 6, which is likely to feature a bigger display compared to the existing models of the smartphone.

Apple is likely to contact owners of older iPhones, who are eligible for the upgrade, via email beginning Thursday to ask them to visit the company’s local retail stores to upgrade to a new iPhone 5s or iPhone 5c, 9to5Mac reported, adding that the event will be held in multiple states across the U.S., and the company will brief its retail management on the event on Tuesday.

According to the report, the new iPhone upgrade program “blends nicely” with the company’s retail store-based iPhone trade-in program, which was introduced in August last year. The program allowed customers to turn in older iPhone models to purchase a new model at a discounted price.

Angela Ahrendts, Apple’s new retail chief as of last week, is expected to oversee the new iPhone upgrade program.

Although there is a growing sentiment among consumers that the smartphone market has become too saturated, Apple's last-quarter iPhone sales touched 43.7 million units, which was a record for the three-month period.

Apple’s new iPhone upgrade program is considered to be in line with discounts from other retailers, such as Target Corporation (NYSE:TGT), which offers the iPhone 5s starting at $119 with contract, while both Best Buy Co. Inc. (NYSE:BBY) and RadioShack Corporation (NYSE:RSH) offer the 16GB model of the device for $99, iDownloadBlog reported.

Apple is believed to be working on other ideas, designed to increase iPhone sales, and according to the 9to5Mac report, all these new programs are also likely aimed at boosting iPhone sales as Apple is expected to release a larger-screened iPhone model later this year.

Rumors are rife that Apple could launch the iPhone 6 in two screen sizes of 4.7 inches and 5.5 inches. The smaller version of the phone is expected to ship first, while the larger version is estimated to ship later due to production issues with the device's display and battery life.