The phone's use of Long-Term Evolution (LTE) wireless technology will allow carriers to increase their charges and boost profits as existing users download more content and smartphone non-converts are tempted to take the plunge.
But despite some new software, relatively minor tweaks to the hardware and an operating system that is starting to show its age risk leaving tech titan Apple trailing competitors such as South Korea's Samsung, and Google.
"The new iPhone will be Apple's most successful smartphone to date," said research firm Ovum from Melbourne.