More likely a hash. But this is another reason that filtering isn't the end solution to the problem. Putting the spammers in jail is. Same goes for mobile spam.
What does suck is that these SPITs will be harder to trace. I'm guessing they will fall under wiretap laws and such.
Fortunately, in the US, Spit would fall under the TCPA (Telephone Consumer Protection Act, not the Trusted Computing Platform Alliance). The US may have lousy anti-spam laws, but the unsolicited commercial telephony laws are at least somewhat useful.
http://www.fcc.gov/cgb/consumerfacts/tcpa.html
Autodialing for commercial solicitation to a residence without prior consent by a for-profit group that you're not already doing business with is automatically subject to a $500 minimum damage per-call.
Tracking down the originator is still a problem, and international senders are a problem, but at least in the case of Spit you've got the law on your side, unlike spam where the law is on the spammer's side (can-spam)
