Here is Verizon's exact statement:
Effective today, legacy Alltel devices can no longer be activated on our network. So, if you had an Alltel device sitting in a drawer or glove compartment and wanted to activate it today, you would not be able to. Today's change does not affect legacy Alltel devices that are currently activated and on our network.
It has been three years since Verizon Wireless purchased Alltel and to give customers the best experience on our network, we are encouraging them to move to current devices. Customers who are told they cannot activate an older Alltel device are able to take advantage of any current promotions, including free devices as offered on our Web site.