The launch event is the first Tim Cook will host as outright boss of Apple
Apple is expected to launch the fifth version of its best-selling iPhone today.
Journalists have been invited to a "Let's talk iPhone" event at its California campus due to start at 10:00 PDT (18:00 BST).
Doubts surround how different the iPhone 5 will be to its predecessor though some do expect big changes.
The launch will be hosted by Tim Cook, now Apple's full time boss following Steve Jobs' retirement in August.
As ever with Apple launches, exact details of product features will not be known until the event. Expert opinion is divided with some expecting significant changes.
"We're expecting a flagship, high tier product to cement the iPhone's position as the must-have device," said Ben Wood, director of research at analysts CCS Insight.