If you’re on Sprint, happen to be poking around your device, and notice that the mobile network type shows as eHRPD followed by a number, the tower your phone is speaking with has received a software upgrade to handle LTE/EVDO handoffs.
In Android, you can view this by going to Settings > About > Network. (I don’t have an iDevice handy at the moment to see what the method is there.)
While this doesn’t mean for certain you’re getting LTE, it does indicate that some of the legwork has been done and that somewhere near you there hopefully should be LTE popping up soon.
To reiterate, the software upgrade can evidently be done without any of the LTE hardware being installed, and it doesn’t mean that you’re on an LTE-capable tower – only that you’re in the vicinity of where a handoff from LTE could occur. So, in other words, this could be getting your hopes up for nothing.
While this is relatively old information as some people have been siting on eHRPD networks for months now, many are seeing LTE pop up now so perhaps there’s hope or a reason to hang on another month if you’re at the end of your rope with Sprint’s 3G network.