Caller ID spoofing
What is Caller ID spoofing?
Caller ID spoofing is the practice of deliberately displaying a false calling number — one the caller doesn't actually own or control — to disguise the true origin of a call, whether for a legitimate purpose (a call center displaying a company's main number instead of an individual agent's line) or a malicious one (impersonating a bank or government agency to commit fraud). STIR/SHAKEN call authentication was built specifically to give terminating carriers a way to detect and flag unverified or likely-spoofed Caller ID before it reaches a subscriber.
More detail
Legitimate spoofing — displaying a business's main number for outbound agent calls — is common and generally allowed, while spoofing intended to defraud or deceive a recipient is illegal under laws like the US Truth in Caller ID Act.
STIR/SHAKEN attestation doesn't stop spoofing outright, but it gives the terminating carrier a verifiable signal about whether the displayed number's use was authenticated, which feeds into spam-likely labeling and call-blocking decisions.
Frequently asked
- Is all Caller ID spoofing illegal?
- No — displaying a business's main line instead of an individual employee's number is common and generally legal. Spoofing becomes illegal under laws like the US Truth in Caller ID Act specifically when done with intent to defraud, deceive, or cause harm.
- How does STIR/SHAKEN relate to spoofed Caller ID?
- STIR/SHAKEN lets the originating carrier cryptographically attest to what it could verify about a call, so the terminating carrier can judge whether a Caller ID is likely authentic or spoofed and label or filter the call accordingly.
See also
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