How can you trace your lost mobile?

Call it. If it has been stolen, report it to the cellular provider so they can put the ESN on the Bandit List. It is possible also that they may be able to tell you what cell zone it is in as well.

If it is being used, they may be able to provide for you the last numbers called. When my daughter's cell phone was stolen, this is what I did. Then, I began calling those numbers and notifying the person who answered that if the $400 phone was not returned within thirty minutes, I would notify the police and give their name and number along with the stolen item report, and they could explain to detectives why they were aiding and abetting the thief in the commission of the felony.

We met the mother of the thief twenty minutes later and recovered the phone, that was "found" by her daughter. My reward for the recovery was to not press charges.