Fair amount of carriers are making the move to upgrade their BES servers 4.0 for example and have started offering public MDS or features to that nature which offers users html browsing on there BB's at no added cost as long as your within you data limits.
The BB recieves service books in two ways, desktop connection or OTA connection to service provider. The Blackberry Browser is another [BrowserConfig] service book. I can't remember if it is delivered by the network or the desktop sync.
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It would depend on who its coming from as to whether or not it would be a desktop application update or an OTA update. If its from a BES server that your company runs, it would be a desktop update (as seen when enabling MDS for a new user - from my experience, they must cradle to get the service book). I will assume that if its a BWC 4.0 update, then it will be an OTA requested update.
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