Bernard included a link to an interesting article that is worth reading when working in the area of emergency services. Here is the abstract of the article “Couple swarmed by SWAT team after 911 ‘hack'”:
A Washington State teenager is facing 18 years in prison on charges that he used his PC to access Orange County, California’s 911 emergency response system and convinced the sheriff’s department into storming an area couple’s home with a heavily armed SWAT team.
This teenager spoofed the telephone number he used for making the emergency call (a mechanism that is quite easy todo in the PSTN due to the lack of security). Then, the phone number is used for retrieving the location of the emergency caller by the emergency services infrastructure. Now, they got location of the place of the caller (but unfortunately the wrong one).