If it is Samsung or other expensive device you can use the factory setup to track it. If somebody tries to open it then you can get a photo of that person. Also if you can't recover that Smartphone you can make it unusable by permanently locking it with your manufacturer's support.
Losing your hand phone may give not only financial lose but also can give you mental stress too.
Because you may lose your online bank account details, important documents, important photos, SMS threads and money more.
So always get a backup for your content in cloud storage or in your PC. Keep record of your phone's IMEI number.
On the phone's box, sellers receipt, under the battery and when press *#06# the screen will display it.
(Once you had bought a new phone find it and should write it down in a paper and keep it in a safe place.)
By using its unique IMEI number, you can recover it or can make the device to be unusable.
In Sri Lanka TRC can get back your mobile phone with the assistance of the police or will make it un-usable with all the carriers, if you make complaint to them. Follow the steps given here.
TRC's special division will go in to action with these details to locate the phone and to recover it, if it is being used with a new SIM card. Also they will inform these details to all the carriers in Sri Lanka.
Mobile phone operators will assist to track the phone using the IMEI number even if they using it with another SIM card from another mobile phone service provider.
If possible they will catch your mobile phone and will return it to you.
Otherwise they will make the phone to be unusable even from any part of the world with a new SIM card. And will inform you by postal letter after some months about their decision regarding your lost mobile phone.
Don't take risk to recover your device with the help of your lost phone app. Always get assistance from the local police to recover the lost mobile phone.
Public holidays, Sundays and Poya days are the best time to make low priced calls to any part of the world from Sri Lanka through out the day and night.
International country code of Sri Lanka is +94 or 0094.