TrueCaller is a unique mobile Caller ID app. with Call Blocker
FreeVcalls has featured an interesting peace of writing: how to trace or locate anonymous mobile phone calls with TrueCaller,
TrueCaller is a cell phone app designed by Software Scandinavia AB which is a Swedish company, this Truecaller mobile caller ID app shows you who is the caller when you receive a call from a phone number which is not stored or saved in your mobile phonebook, and this also works with outgoing calls,
TrueCaller or the True Mobile Caller ID app is like a reverse phone call locator and is a cool mobile app which gives real time info of anonymous or the unknown callers, this mobile app currently works in 25+ nations viz. USA, Canada, INDIA, Sweden, France Italy Denmark etc, but sorry no UK here,
It works on various mobile OS like Android, Symbian, Windows Mobile, iPhone etc and more than 500 mobile handset / devices,
Watch the truecaller YouTube videos:
In few nations or some companies their back-end system adds few digits in beginning or at end of the phone number of an incoming call to indicate something, Like in few companies they use to add a set of few digits just to indicate that this call is a forwarded call or that it is merely a internal call within the company etc.
With TrueCaller call tracer app still you can locate the callers though your system adds digits by simply removing them!