That confirms my suspicions that BlackBerry are targeting particular phone models and then selecting in model order via the most widely used type in each carrier per country.
That's why we see, for instance, Passports updating before Z30s on one particular carrier network, whilst on another carrier the Passports could still be waiting whilst other more numerous models get the update first. And this seems to be regardless of whether a phone is carrier-locked or not, as it appears to depend on the particular carrier sim card in the phone. Hence, my factory-unlocked Z30 in UK received update with a Vodafone sim but not with an EE sim.
Furthermore, perhaps the whole update rollout is being staggered due to BB10 divisional budgetary restraints on the downloading bandwidth capacity of BlackBerry's BB10 update servers.
- And, no doubt, BlackBerry will remain tight-lipped if asked whether the above is indeed so!