I just purchased this same plan today and had no issues with calling, but did have a problem with texting (message would not go through). This problem persisted until I reset my device and tried again. Have you tried rebooting your phone and calling ...
I've just signed up for a plan today with 1 gig of 3G data and have also been given access to the LTE network. I can only assume that it's temporary and is due to our new activations. It sure will be nice while it lasts! Welcome!
