You can check at Verizon's FiOS Qualification page by either:
1. Entering your address or
2. Entering your Verizon telephone number.
If you use your telephone number, the system will check for FiOS and -- absent that -- DSL availability. It also allows you to sign up for future notification of FiOS availability. Sometimes a person's phone number will say FiOS is not available. However if you put in your address and it comes up that FiOS is available but they just don't allow on line ordering at this time, call the number as displayed to order services.
If you use your address, the system does not additionally check for DSL availability but does allow you to sign up for future notification. Be sure to have a valid e-mail address, as well.