I'm a customer with Verizon wireless, and I know they have discounted upgrade programs, but would like to know how often I'm allowed to upgrade my phone at these discount prices. I can't afford to pay full price for a new phone.
You can usually upgrade your phone once a year. If Verizon isn't allowing you to do this, go ahead and switch to another carrier, because everyone else will let you upgrade.
With verizon it depends on how long your contract is. With their one year plan you can upgrade your phone at a discounted price in 10 months from start of contract. With their two year plan you can upgrade in 20 months with even greater discounts.
Discounted prices are dependent on your specific plan. Traditionally you are allowed to upgrade your phone every 2 years (accepting a new 2 year contract).