From John Schwartz’s “Text Hackers Could Jam Cellphones, a Paper Says“:
Malicious hackers could take down cellular networks in large cities by inundating their popular text-messaging services with the equivalent of spam, said computer security researchers, who will announce the findings of their research today.
Such an attack is possible, the researchers say, because cellphone companies provide the text-messaging service to their networks in a way that could allow an attacker who jams the message system to disable the voice network as well.
And because the message services are accessible through the Internet, cellular networks are open to the denial-of-service attacks that occur regularly online, in which computers send so many messages or commands to a target that the rogue data blocks other machines from connecting.
By pushing 165 messages a second into the network, said Patrick D. McDaniel, a professor of computer science and engineering at Pennsylvania State University and the lead researcher on the paper, “you can congest all of Manhattan.”
Also see http://www.smsanalysis.org/.