Apparently, the Sony SGP621, which has also been touted by some to be the Sony Xperia Z3 Tablet, will arrive with LTE connectivity built right into it. After all, if one were to follow a similar pattern that has been established by the LTE models of previous Sony Xperia Z series tablets, then it is only a logical conclusion that the SGP621 will be the Xperia Z3 Tablet. For instance, the Xperia Z Tablet is known as the SGP321, while the Xperia Z2 Tablet is called the SGP521.
Still, it would be wise to take this with a pinch of salt, at least until Sony comes clean at their press event at IFA 2014 in Berlin, Germany, next month. Hopefully the Xperia Z3 Tablet will continue to maintain its water resistance capability.