Verizon officially retired analog cellular phone service on February 18, 2008. No further analog calls can be placed or received on the Verizon network.
For the past several years, they have been not-so-subtly encouraging their users to upgrade to "better" digital cellular phones, and announcing the impending termination of analog service as an incentive to make the change.
Verizon's analog services were utilized the original cellular phone system, Advanced Mobile Phone System, or AMPS. Cellular provider apparently Alltel has apparently shown the intention to convert the remaining analog regions of their network to digital by the end of 2008.
Verizon and Alltel will be eager to reuse these frequencies for digital cellular services - where digital compression and multiplexing strategies will allow a far greater number of calls to be handled in a given cell.