I had a Kyocera 7135[1] back before the Treos took off, pretty incredible for the time. No concept of a "data" plan, all my bits came from dialing up a cellular line like old school modems.

I'd actually argue that the precursor to the modern smartphone was the Sidekick. It was one of the first ones with push IM, email(even for pop3!) that worked well with consumer's interests in mind. Sadly it never went anywhere other than t-mobile in the US. Andy Rubin did go on to build Android with large parts of that team so not all was wasted.

[1] https://www.phonescoop.com/phones/phone.php?p=173