// Understanding ANI & CPN with VoIP
//
// by Doug Brickner
//
// http://www.oldskoolphreak.com

ANI (Automatic Number Identification) & CPN (Calling
Party Number) has always been very confusing.  
Especially now with VoIP (Voice Over IP) telephones.  
This article will explain to you the difference of 
what Vonage, VoicePulse and a few other VoIP providers 
send as ANI & CPN/Caller ID when using their Caller ID 
block feature.  

When you place a call the switch logs the time of
call, the number you're calling from and the number
you're calling to.  If the switch is SS7 compatible
(which 99.99% of switches are), then the switch sends
your ANI and CPN along in a packet of data. The ANI
is the number you called from, and so is the CPN 
(assuming you're using a regular telephone line).
If you're using a PBX/PaBX system with trunks then
you may have to specify your CPN on your outgoing
calls, as DOD trunks do not have phone numbers 
associated with them since they are 
Direct -Outwards - Dialing, in other words, the 
DOD is specifically meant to make calls, not receive 
them.

Vonage does this almost like a regular land line.  
Your CPN and Caller ID are sent fine.  If you use *67 
they send a private tag but the CPN is still sent.  
But the ANI is always going to be some 10 digit number 
that belongs to Vonage.  This number is just some disconnected 
number when you call it. This is because realtime ANI 
doesn't really work with VoIP because VoIP isn't exactly 
a real telephone line.  So the CPN is "spoofed" as the 
Vonage customer's VoIP telephone number.  

Here is a chart of what your ANI/CPN/CID is like with Vonage, 
VoicePulse, and Packet8 when using the Caller ID block feature.

--
	VONAGE Blocked/*67
973-954-4049		ANI
Your Vonage Number	CPN
"PRIVATE"		Caller ID  Box

	VONAGE Unblocked
973-954-4049		ANI
Your Vonage Number	CPN
Your Vonage Number	Caller ID Box

--
	VOICEPULSE Blocked/*67
646-619-5149 		ANI
212-400-7400		CPN
"PRIVATE"		Caller ID Box


	VOICEPULSE Unblocked/*82
646-619-5149		ANI
Your VoicePulse Number	CPN
Your VoicePulse Number	Caller ID Box

--
	PACKET8 Blocked
NO ANI				ANI
040-361-6210 			CPN
040-361-6210			Caller ID Box

	PACKET8 Unblocked
NO ANI	 		ANI
Your Packet8 Number	CPN
Your Packet8 Number	Caller ID Box
--


When you have your Caller ID blocked, VoicePulse
sets a private tag but also changes your CPN to
a 212-400 number that they own which happens to 
be disconnected.  When Caller ID is unblocked 
(or you use *82) VoicePulse will send the proper 
CPN as your VoicePulse number allowing it to be 
sent to Caller ID boxes. VoicePulse's and Vonage's 
realtime ANI is also some other disconnected number.  

Why VoicePulse changes your CPN to their 212 number
AND sends a private tag for caller ID? I have no idea.
Maybe it's because they believe sending Private isn't enough,
they also have to send a fake CPN so nobody can get back to you.

VoicePulse is a good way to go. Because when you block 
your number, all people will get is some disconnected 
numbers.  Now can that get traced back to you?  Of 
course it can.  They can find out it's VoicePulse and 
VoicePulse can find out easily it's you.  That's why you 
should never do anything too stupid.  


I tested all of this is with ANACs. 
1-866-MY-ANI-IS 
(Even though it says ANI. It IS reading the CPN)

Sorry, I can't give you any real time ANACs.  The ones 
that I use are toll free that don't require any kind of 
password; those are hard to find. 

Speaking of ANACs, you should also know that 1-800-444-4444 
does NOT read CPN.  It reads Caller ID then if Caller ID 
is blocked it reads the ANI.  Now I know you're 
probably thinking What the hell?! CPN is Caller ID 
you n00b!  Well yes, Caller ID is generated by CPN.
However All 800-444-4444 does is look for the caller ID 
information.  If it receives Private or any kind of 
bullshit kind of number it therefore goes and grabs 
the real time ANI.  Why it does this.  I don't know. 

The perfect way to test this is with Vonage.
I explained how Vonage's realtime is a 973-954-4049 
number and Vonage's CPN is ALWAYS going to be your Vonage 
number. Well if your *67-1-800-444-4444 with Vonage.  You'll 
notice it looked for the Caller ID, but of course it was 
private so therefore it grabbed your Realtime which is the 
973-954-4049 number instead of your Vonage number. 

Even though if I call *67-1-866-MY-ANI-IS with Vonage
it will still read my CPN.  Another way is to test this 
with certain kinds of calling cards, knowing what they
pass for ANI, CPN, and if they block Caller ID or not.  


You can also always use a soft phone application with an IAX
provider so you can spoof any CPN you would like.  It's also 
good to find a good open access VoIP provider that doesn't
have a real time ANI at all either.  

It will make you anonymous...
but everything can still be traced.



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