Phone from a known number can also be Fraud!Know How..

If you are suspicious about a call then check that number by calling back whether it was really from a known person or not because by fake call app only caller Id is changed. In reality call does not come from that number. There are a number of applications and websites that can call by hiding your identity. You can also ascertain the number which will display when you call.
Messages can also be sent.Some apps can change voice also.But you have to pay for such apps.

Caller ID will be hidden
They can determine which caller ID will be displayed.

Voice can be changed
Spoofcard app gives the facility of changing voice in addition to changing caller is.

Messaging by hiding identity
There are many websites through which messages can be sent to any mobile number .You don't even have to register for them.
Such calls cannot be traced but service provider of messages coming from unknown number can be identified. Eg.if a msg comes from a code instead of a number eg. IA chat or any other code then you can submit it to www.indiatrace.com/trace-bulk-sms-sender/
By this you can know service provider, that the site sending msg is taking, the service of which company-Airtel,Vodafone or any other.