Step 1. Contact your local police dept.
This is to file a police report for a lost or stolen phone. While it may not seem like an important thing to do , having a police report does come in handy when dealing with warranty service and your cell phone provider.
Step 2. Contact your cell phone provider.
This is to inform them of the lost or stolen phone so that no new charges will be applied to your account for calls that you did not make. They also will be able to assist you in finding or tracking your cell phone and will also recomend a course of action.
Step 3. Finding or disabiling the phone.
If your phone was lost then there are things that you can do to try and locate it or just diable it.
This link is to register your phone with an online data base and the reason for this is that if found you can ge notified of it coming into thier data base.
This next link is also a way to have your phone returned to you if it was lost and someone finds it.
This next link is one that can be applied to your phone in an attempt to locate the phone using gps and you can disable it and even erase the contents if you choose.
Step 4. Locating a stolen phone.
It is not recomended that you attempt to recover your stolen phone as it may lead to serious injuries from a confrotation that may occur in attempting to get the phone yourself.
You can track the phone and identify it's location but you should then notify the authorities as to it's location so that they can recover it for you.
These next links are for attempting to track your phone using the imei number of the phone. Each cell phone is given a unique set of numbers to identify it and it is what the cell phone providers use to register the phone with thier service.
Tracking by sim card is not as efficient as the imei number because the sim card needs to be powered up to see it. The sim card can also be removed and another put in it's place to make the phone able to be used, the imei number can't be removed. You may be better off just diabling the sim card it so that it can't be used and calls be applied to your account.