NIST SP 800-63B-4 says verifiers SHOULD consider risk indicators such as device swap, SIM change and number porting before using the PSTN to deliver an out-of-band secret.

Checked 2026-09-30

Verifiers SHOULD consider risk indicators (e.g., device swap, SIM change, number porting, other abnormal behavior) before using the PSTN to deliver an out-of-band authentication secret.
Vendor
NIST
Product
SP 800-63B-4
Subsystem
out-of-band authenticators
Deployment
any
Region
us
Release range
revision 4
Checked
2026-09-30

Sources

Cite this note

APA

WarmTransfer. (2026, September 30). Caller authentication and fraud prevention in contact centers: source note contact-center-caller-authentication-nist-pstn-risk-signals. WarmTransfer. https://warmtransfer.net/knowledge/claims/contact-center-caller-authentication-nist-pstn-risk-signals

BibTeX

@misc{warmtransfer-claim-contact-center-caller-authentication-nist-pstn-risk-signals,
  title  = {Caller authentication and fraud prevention in contact centers: source note contact-center-caller-authentication-nist-pstn-risk-signals},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/contact-center-caller-authentication-nist-pstn-risk-signals},
  note   = {Source note contact-center-caller-authentication-nist-pstn-risk-signals, checked 2026-09-30}
}

Read in context