Apple is expected to announce the newest version of the iPhone at a 10 a.m. event Wednesday in San Francisco.
The company hasn't specified the topic of the event, but email invitations to reporters contained a shadow in the shape of a "5", the next version in the iPhone series.
The announcement is being held at Yerba Buena Center for the Arts Theater, a site for many Apple product launches.
The new edition is expected to work with 4G - fourth-generation - cellular networks, a feature that rivals have already incorporated. Experts have speculated that the new iPhone will have a slightly larger screen as well.
The model is expected to go on sale a week or two after the announcment.
While sales of iPhones are still strong, Apple lost the lead to Samsung this year. Samsung released the Galaxy S III in the U.S. in June, several months of the expected Apple release.
Apple is also expected to update its phone software, including dropping Google Maps for its own service.
The rivalry between Apple and Google continues to intensify, as Google said Tuesday it will release a new YouTube app for iPhone and iPad. A five-year licensiing agreement is expiring that established YouTube as a built-in application for Apple mobile devices.
Amazon, Nokia, and Motorola all had events to generate interest in their products last week, hoping to boost sales.
Amazon unveiled four new models of their Kindle Fire, while Nokia and Motorola announcement a total of five new smartphones.
It is unknown whether Apple will announce a smaller version of its iPad at the event Wednesday. Apple dominates the tablet market, selling seven of every 10 tablets worldwide in the second quarter, the AP reported.
Competitors have tried to compete by producing smaller, cheaper models, such as Amazon's Kindle Fire. A mini iPad would challenge these smaller models.