The RIM-900 was one of the first wireless data devices, marketed as a two-way pager. It operated on the Mobitex network. It was a clam shell device that could fit on your belt. It had a small QWERTY keyboard for sending and receiving email and interactive messages.
The product was introduced as Inter@ctive Paging in 1996 by Research in Motion and RAM Mobile Data.
References
RIM-900 Wikipedia(Text) CC BY-SA