[Laforet]

Indeed, this has been an issue since the 3G era. I live in New Zealand. 10 years ago one of the largest local carriers switched from CDMA to WCDMA-only using the exotic North American 850MHz band whereas all other carriers use the more common 900MHz. They also both have 2100MHz base stations in busier urban areas.

This caused endless headaches for users and tech support alike because the market was flooded with phones that might have 850MHz support. There is no way to tell from the model or serial number - even Samsung and Nokia often failed to properly indicate that in their specs. And because both networks were also on 2100MHz, a phone may appear to work fine for months, but you will find out the hard way when reception completely disappears in a slightly remote area. There was also no GSM to fall back to since they built it from the ground up with no 2G layer.

Legend has it that one intrepid phone reseller would routinely take his stock on a boat to a spot 15km away from the nearest shore where no 2100MHz signal could reach, and only there could one be sure that the reception you are getting is on the 850MHz band.