Ten years older. I'm from West-Europe and most people only got dumbphones around the time I was 18-19 (~2000 and mostly adults or 17-18 year olds). Phones with cameras became widespread quite a few years later. Even when I got an iPhone in 2009, most people were still using good old dumbphone/feature phone Nokias. After 2009 it changed very quickly. I think that aligns with you being 10 years younger + adoption in the US (assuming that you are in the US) being earlier.

Phones were simply not a factor when I was in high school. If you had to call someone on-the-go, you would use one of the many public phone booths and a pre-charged card (there were always rumors that you could spay them with hairspray to get unlimited credit :D). But that almost never happened, you'd mostly just meet people IRL if you wanted to socialize.