You can google the address if it's not local. You can also go to the internet for personal or business addresses. if it is local , you know the name of the business or person's name you look through your yellow pages. Contact people who might know that place or person.
In most instances, you can dial 411 from you cell phone, give them the address and they will give you a phone number. This does cost money and how much would depend on where you are (city, state, etc.).
You are going to have to either contact the person by mail or you will have to go by the address. That way, you can either ask them directly for their phone number. Or you can write them by mail and inquire their phone number too.
Basically the cheapest way to get a phone fat is to buy a prepaid phone. Otherwise you will have to sign up for a cell contract or a traditional land-line.