Good point, the ones at airports could more readily support passports, as opposed to a street-side authorized (or grey market) shop. More recently I've used Goo

Good point, the ones at airports could more readily support passports, as opposed to a street-side authorized (or grey market) shop. More recently I've used Google Fi, which has the benefit of roaming on both Unicom and Mobile depending on signal strength, in addition to full internet access.