If you're out and about and notice your gear missing, it's no time to go into panic mode. Calm down, say a silent prayer and get started on these tasks:
Call your phone.
As soon as you realize your phone is missing, call it. Use a friend's phone, or ask the barista to use the handset behind the counter. You could even make a call from a web service like Google Voice. Your "stolen" phone could just be a case of mistaken identity (these kinds of things can happen when every hipster in Brooklyn carries the same iPhone 4).
Activate a locator or tracker (if you have one).
If you had the fore-thought to activate a remote GPS locator on your phone, this is the time to tap in. Apps like Find My iPhone, GadgetTrak and Where's my Droid? can take photos of the thief and relay the current location of your phone to your email inbox.
Log in to your carrier's website.
Log in online and check your phone activity to see if the thief's made any phone calls or text messages that might help you identify who they are or where they're from. Save the records, too, in case you need them as proof for police.
Call your carrier and report it stolen.
If you can tackle the first three steps quickly (in a minute or two), you can wait to report your phone stolen. Once your carrier shuts off service, you won't be able to activate a tracker or watch for new text messages. But if you can't get to a computer (or you see a bunch of expensive calls have already been made), call and report your phone stolen right away so your carrier can cut off service.
Change your passwords.
If you have any login or password info saved in your phone, you'll want to change the passwords for each of those services. Everything from iTunes to your checking account could be compromised in seconds. You can also deny access to your devices from sites like Facebook and Twitter.
File a report with the local police.
It's a good idea to report your phone stolen by heading to a nearby police precinct with your phone's information, like the model number, serial number and that usage report you saved earlier. You'll increase your chance of getting the phone back, and you might need a report to file an insurance claim to replace your phone.
Replace your phone and reactivate your service.
Check and see if your phone is covered by any available warranties or insurance plans (don't forget to check with your credit card and/or your homeowner's or renter's insurance companies), you might be able to have your phone replaced free of charge. If not, and you are due for an upgrade, this might be the perfect time to level up and get a new smartphone. Otherwise, try to borrow a friend's phone or snag a deal on a used smartphone online.