Check the IMEI number: Every iPhone has a unique IMEI number, which can be found by dialing *#06# on the phone. You can also find the IMEI number on the box or on the back of the phone. You can check the authenticity of the IMEI number on the official Apple website. Check the hardware: Original iPhones have high-quality construction, with smooth edges and a polished finish. They should not have any rough edges, gaps, or misaligned parts. The buttons should be firm and responsive, and the camera lens should be flush with the back of the phone. Check the software: Original iPhones run on the latest version of iOS and have the standard Apple apps pre-installed. If the phone runs on a different operating system or has non-standard apps, it may be a counterfeit. It's worth noting that even with all the above checks, some counterfeit devices are made very similar to the original ones, so it's best to purchase from reputable retailers and resellers.