CDMA carriers have complete and utter control over every aspect of a device on their network (including updates). Where GSM carriers have no control except when contractually agreed upon by the manufacturer. This is why Verizon can "certify" its devices, and block any other devices from working on its network, while if a GSM phone is physically capable of operating on a carrier's network, the carrier MUST allow it. Basically it can be looked at as on GSM, an update's final say lies with the manufacturer, where on CDMA, the final say lies with the carrier.