NumberGlossaryCaller ID Spoofing
US (Truth in Caller ID Act / FCC); Canada (CRTC) parallel · also called spoofing, number spoofing, caller ID falsification
Deliberately falsifying the calling number or name transmitted with a call so a different identity shows on the recipient's device.
Caller ID spoofing is when a caller deliberately falsifies the information transmitted to a recipient's caller ID display to disguise their identity, causing a number or name other than the true originating one to appear. It is technically possible because caller ID (the calling number, and via CNAM the name) is signaled along with the call and was historically passed through and displayed without authenticating whether the transmitting party was entitled to that number. Scammers exploit this with tactics like "neighbor spoofing" (making a call appear to come from a local number) or impersonating a trusted company or agency.
In the US, the Truth in Caller ID Act and FCC rules prohibit transmitting misleading or inaccurate caller ID information with the intent to defraud, cause harm, or wrongfully obtain anything of value; violators can face penalties of up to $10,000 for each violation. Spoofing is not always illegal, however — legitimate uses exist, such as a doctor displaying the office number rather than a personal mobile, or a business displaying its toll-free call-back number. To combat illegal spoofing, the industry developed the STIR/SHAKEN caller ID authentication framework, which lets the originating provider cryptographically attest to a number and the terminating provider verify it was not altered.
Not all caller ID spoofing is illegal. Under the Truth in Caller ID Act it is unlawful only when done with intent to defraud, cause harm, or wrongfully obtain something of value; legitimate business and professional uses are permitted. Likewise, a spoofed call does not mean the person who owns the displayed number is the caller — that number's owner is usually an unrelated victim whose number was falsely transmitted.