Understand Voice-over-IP numbers, STIR/SHAKEN attestation, and why SIM-routed numbers pass verification that VoIP cannot.
Jul 22, 2026•Telecom Desk•6 min read
A VoIP (Voice-over-IP) number is a phone number provisioned in software rather than on a physical SIM. Services like Twilio and Google Voice assign VoIP numbers programmatically, which makes them attractive for automation — and which is exactly why platforms block them.
Why Platforms Block VoIP
Fraud rings have long used bulk VoIP numbers to create armies of fake accounts. In response, major platforms maintain live blacklists of VoIP prefixes and use STIR/SHAKEN attestation to verify that a call or SMS originates from a legitimate carrier. VoIP numbers fail this check and are rejected at registration.
Why SIM routing wins: TempNova’s virtual numbers terminate on physical SIM-carrier gateways, presenting genuine mobile network metadata that passes validation VoIP cannot.
For developers automating verification, this distinction is the difference between a green test and a perpetual failure. Allocate a SIM-routed number via the API to mirror real user conditions. For background, see our developer’s guide to OTP verification.
Key Takeaways
Use disposable email addresses and virtual phone numbers to protect your real identity online
TempNova's sandboxed iframe reader prevents tracking pixels from leaking your IP and device data
Stateless architecture means no data is permanently stored on TempNova's servers
Virtual phone numbers route through real SIM-carrier gateways for maximum platform compatibility
Disclaimer: The information provided in this article is for educational purposes only. TempNova tools are intended for legitimate privacy protection, spam prevention, and software testing. Using temporary communication services for fraudulent activities, identity theft, harassment, or any illegal purpose is strictly prohibited. Always comply with applicable laws and the terms of service of platforms you interact with.
About the author
Telecom Desk — TempNova Telecom Engineering. The Telecom Desk covers the carrier-grade infrastructure behind TempNova’s virtual SMS numbers, including SIM routing, OTP delivery, and why physical carrier gateways outperform VoIP for verification.
