How do you become an Iphone beta tester?

You may have to become involved and active in a software capacity before such an event

may occur; such as the https://appleseed.apple.com/sp/welcome where you'd be invited.

Or the software beta program: https://appleseed.apple.com/sp/betaprogram/ -- and/or the

Apple Developer site: https://developer.apple.com/

Other beta programs and developer program information is locatable by searching Apple

sections, and perhaps in a developer discussions area (register as developer) such a

question as yours could be more accurately answered. But not in an open regular ASC.

Hardware is generally not supplied by Apple in the programs I was invited into, and as

such, I asked to decline participation due to not having a new enough model device.

Perhaps someone would be kind enough to point you (or relocate this question) to a more

suitable discussions area; but you likely would have to go into an area yourself & register

or see what requirements and conditions of the software developer or seed programs are.

In any event...

Good luck! 🙂

Just to be clear there is no iPhone beta test program, as in people who get pre-release iPhone models. There is a beta test program for iOS and OS X - the software operating systems that run on iDevices and Apple computers. Beta testers provide and use their own hardware.