We currently only have the Motorola DynaTAC 8000X which is a 2 slot phone in the Inv. I would like to recommend the Motorola 9800X which came out in 1989, Which I know is a year later in-game time However we already have a bunch of stuff from the future in the server anyhow. Perhaps the cost in the store could a premium to justify the size.
9800X 8000X