NIST SP 800-63B-4 classifies out-of-band authentication over the PSTN (SMS or voice) as a restricted authenticator.
Checked 2026-09-30
Use of the PSTN for out-of-band verification is restricted
- 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
- NIST SP 800-63B-4 Digital Identity Guidelines: Authentication and Authenticator Management — National Institute of Standards and Technology · tier 1 standards and regulators · Sec. 3.1.3.3 Authentication Using the Public Switched Telephone Network
Cite this note
APA
WarmTransfer. (2026, September 30). Caller authentication and fraud prevention in contact centers: source note contact-center-caller-authentication-nist-pstn-restricted. WarmTransfer. https://warmtransfer.net/knowledge/claims/contact-center-caller-authentication-nist-pstn-restricted
BibTeX
@misc{warmtransfer-claim-contact-center-caller-authentication-nist-pstn-restricted,
title = {Caller authentication and fraud prevention in contact centers: source note contact-center-caller-authentication-nist-pstn-restricted},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/contact-center-caller-authentication-nist-pstn-restricted},
note = {Source note contact-center-caller-authentication-nist-pstn-restricted, checked 2026-09-30}
}