How to Fake Your Caller ID with Asterisk

The Whole Point

Basically, you're gonna set up your own private phone system that lets you change the number that pops up on someone's phone when you call them. It's like putting on a digital mask.

What You Gotta Have:

• An old computer (even a rusty one works) running Linux (like Ubuntu Server). You don't need a beast.

• Asterisk installed on that machine.

• A VoIP provider account (something like NuFone or VoicePulse that lets you use your own gear). Think of them as the middleman that connects your call to the real world.

• A softphone on your computer (like X-Lite or Twinkle) that's the app you'll use to actually make calls.

The Three Files That Run the Show

All the action happens in three text files inside /etc/asterisk/. You just gotta edit them. iax.conf This file links your Asterisk box to your VoIP provider. You just paste in the server address and your login details they gave you.

[my_provider] type=peer host=provider.server.com username=your_username secret=your_password

sip.conf – This creates user accounts for your softphones (the apps on your computer) to log into your Asterisk system.

[my_softphone] type=peer host=dynamic username=allan secret=1234 context=outgoing

extensions.conf This is the brain. It tells Asterisk what to do with calls. Here's where you drop the line to change the caller ID. Check this simple rule for US numbers:

[outgoing] exten => _1NXXNXXXXXX,1,SetCallerID(2024561111) exten => _1NXXNXXXXXX,n,Dial(IAX2/my_provider/${EXTEN})

The magic is SetCallerID(2024561111) swap that number with whatever you want to show on the victim's screen. The next line sends the call out through your provider.

How to Make It Work

• Fire up your softphone (like X-Lite) and tell it to connect to your Asterisk server (the IP of your Linux machine) using the username/password you set in sip.conf.

• Dial any number using the softphone. Asterisk catches it, applies the fake caller ID from extensions.conf, and shoots it out through your provider.

• The person you're calling sees the fake number you chose.

I wan to add that you would need access to a carrier (MVNO) which will allow you to edit the CID field they have preset in their headers. Some carrier's allow their consumers to bypass this field, but most of the time it doesn't last long. Another thing is Stir/Shaken Protocalls, and Attestation. These two factor's will show if your call will land on big known carrier's in various countries.

Attestation A - is one of the best you could get which means you're Stir/Shaken Verified, and all header's are correctly configured. If you are able to achieve that you should be able to continue with whatever you are doing. However once you get a traceback from the FCC, which comes after a few hundred to thousand calls the carrier will be forced to shutdown your trunk account.