is there a way in IOS 7 that can block phone numbers that are not in my contacts?

if you get a call from someone you can block them from the recent call list

Also you can go to Settings/Phone/Blocked

there is an Add New Option to add a phone number (scroll down to the bottom of the screen to see it)

I believe blocking a person from calling you also blocks them from sending you SMS and Imessage messages

Set up DO Not Disturb, but allow exceptions for your Contacts.

actually the answer about using Do not disturb is probably a better one - that way you dont need to wait for calls to come in before you blocj anything thats not in your contact list(if thats your intent)