EDGE, Not 3G
These days few people have even heard of EDGE, or Enhanced Data rates for GSM Evolution, a second-generation cellular data technology that has long since been superseded by 3G and 4G/LTE — and soon 5G. However, when the original iPhone was released, EDGE was the dominant cellular service. Third-generation, or “3G” wireless data had become available the year before, but it was too new for Apple, which preferred to bide its time and stick to more established standards. This meant that the original iPhone had a whopping maximum theoretical throughput of 384 kbps. Yes, that’s a “k” as in kilobits per second, meaning that the original iPhone couldn’t even reach 1 Mbps.
Mind you, this wasn’t as much of a limitation as it may have seemed. In those days, cellular data was still very expensive — it wasn’t uncommon to pay up to $100/month for a paltry 200–500 MB of data — and while Apple and AT&T broke new ground by offering unlimited data plans for iPhone users, AT&T may have been less eager to do so if the new iPhone was running on its 3G network instead of its older and slower EDGE network.