Comments on: Hacking Caller ID: unblocking blocked phone numbers

Defensive telephony rather than computing

[powder1122]

Wow! must have taken him about 15 min to learn that! Silly little privacy header. If this is a shock to anyone please go back to finger painting.

[oneoclock]

This depends entirely on your telephone service provider. Most businesses are hooked up to the public telephone network via ISDN. In this case it depends on the phone company. Most residential and small business phone lines are analog phone lines. On an analog phone line you never get a caller ID signal if caller ID was withheld by the caller. NEVER. Most medium to large businesses are connected to the public phone network via ISDN. Most phone companies will not provide any caller ID via ISDN if the caller withheld caller ID, all they send is a header that tells the called party why there is no caller ID. Only very large businesses are hooked up to the public phone network via SS7, in which case they may obtain caller ID even if it was withheld by the caller. Phone companies also hook up to each other via SS7, so they may also obtain caller ID even if withheld.

What Mitnick demonstrated sounds like his route was all SIP (a voip protocol). Well, most of the world's phone calls travel over SS7 and ISDN, not SIP. Even if it voip is involved, there are several other protocols, many of which do not provide withheld information as freely as SIP does. This is a storm in a waterglass. After all, if you use SIP, in many cases the media travels directly between the end points and then the called party can see your IP address even if they couldn't see your caller ID, or if you used a fake caller ID. In other words, SIP doesn't provide privacy anyway due to the nature of a p2p IP media path.

[Kev Orng]

I just don't answer those calls that come up as private or unknown.
If it's important, or someone I know, they'll leave a message. If they're trying to sell something, they don't.
It's a lot easier than routing home calls through servers to your cell phone so you can look at a phone number and make the same decision.

[yogumca]

i dont now

[fourthconstruct]

i had a friend who i would prank call all the time with random voice changers and sound boards, it was hilarious! But then that bastard evolved... he wouldn't answer private calls or from my number lol. So i evolved too! I spoofed my number to be his work and i used a voice changer and said i was his boss lol! I got my spoof card from freespoofcard.blogspot.com! Hahaha its awesome u guys should try messing with someone by changing the caller ID it shows for them!

[ECASCIATO]

Hello Michael,
We recently have been getting prank calls on my wife's business phone. Annoying and irritating but nothing more. Yesterday her caller ID was not her business name when she would make an outgoing call. Of no coincendence the name on the caller ID was that of the suspected harrasser's previous address. It was like a signature to let us know it was him. We contaced ATT and they were no help to find out how this was done. The caller name only changes on the local cable phone network. How serious of a problem is this as we have credit card numbers processed on this phone line. Where can I turn to and what can be done.
Ed Casciato
[e-mail]