In 1993 and 1994, when I worked for an office supply chain, I programmed a couple of these bricks (and, I think, one early flip phone, see below) for customers who came in and bought them off the floor (so to speak: they’d bring a product card to the cash, matching the product we kept in management’s booth). Motorola and/or the carrier supplied binders with step-by-step instructions for the reseller to key in the info to activate a unit.
What I remember is how long, complicated, slow, and convoluted it was to do this. It was literal keying in long strings of numbers (like what I guess would be IMEI or equivalent), strings for the carrier ID, and so on. And those poor displays couldn’t show all the digits in a long string, so screwing things up required starting over.
It was not fun, absolutely nothing like setting up a new device now, and at the time, left me thinking mobile phones would always be a business/luxury item. Of course, fast-forward to late 2000…