The more the merrier! You can use addresses and phone numbers from guests around the world.
Our guest addressing tool is formatted for US addresses though. When you order your invitations you will need to manually review and correct the addresses for your international guests.
If you're unsure how to format your international addresses you can take a peek at this USPS FAQ.
We're here to help if you have more questions on international guests (or anything else!) support@zola.com or (408)657-9652.