What to do if iphone is stolen?

What to do if iphone is stolen?

You steal someone else's.

I think you can track it because before you get it you go through a system!

Also call the police I'm pretty sure they can track exactly where it is

Call the police if necessary!

Call your operator and ask to lock your phone number and if possible, to block the phone entirely (by its IMEI code - you can find this written on the box you bought it in, or in the papers).
If you have an antivirus like Avast, or a Samsung account, there are some more possibilities: lock the phone by yourself, take and send to yourself pictures of the offender, find out it's GPS position, erase all your sensitive personal data etc.

Use someone else's phone, call your phone carrier and go through opts to temporarily disable your phone.
Then when you find or purchase a new phone you will go through the same process to enable.