What Is a VoIP Number — and Why Apps Reject It

By ComparaSMS editorial team · Updated October 2026 · What changed

A VoIP number runs over the internet rather than a mobile carrier's SIM. Google Voice, TextNow and most second-number apps use VoIP.

Why apps care

Apps look up the line type in carrier databases. VoIP numbers are cheap to create in bulk, so banks, dating apps and marketplaces often block them.

When you need non-VoIP

• Banks and payment apps
• Tinder, Bumble
• Walmart

See non-VoIP numbers.

How apps detect VoIP

Each phone number belongs to a carrier, and carrier databases record the line type: mobile, landline or VoIP. Apps query these databases during sign-up and decide whether to send the code.

VoIP vs non-VoIP in practice