Call Spoofing Software.

Hello Null-Byte Users and Admins. Its an honor to be a part of this reputable website. As this is my first questioning or writing an article, whatever may the correct terminology be I leave that up to you. The question I want to ask is about as the title says "Call Spoofing Software", I was watching a TV series called "Hannibal" in which the "Tooth Fairy" calls "Dr.Lecter" and was using a call spoofing software to spoof his number with Dr.Lecter's Lawyer.

Can you guys please tell me more about these call spoofing software and one more thing, This is the first time I'm asking a question here to please refrain from saying that "Google it" as I'll be doing that as well. I want your opinion on this matter.

Hoping to get positive response ASAP.

The_Unknown