Please provide links to the relevant regulations from an actual government website such as eCFR in the US (https://www.ecfr.gov/)
The regulation would likely come from an industry body like the GSM alliance or some other thing that gates certification without which carriers won't allow the phone model onto their network, not governments.
The regulation would likely come from an industry body like the GSM alliance or some other thing that gates certification without which carriers won't allow the phone model onto their network, not governments.