Is Google Voice a VoIP number? How it is classed
Why a Google Voice number fails where a SIM-based mobile number passes.
How do databases class Google Voice?
Twilio defines "nonFixedVoip" as "a virtual phone number obtained online without requiring a physical device. For example, Google Voice or Enflick." Enflick is the company behind TextNow. Most US sign-up forms that check line type rely on this kind of classification.
Which services refuse it?
| Service | What its help centre says |
|---|---|
| OpenAI (ChatGPT) | Does not support landline, VoIP, Google Voice or premium numbers for verification |
| Microsoft | "VOIP numbers cannot be added as a way to sign in or get verification codes." |
| Telegram | "Telegram accounts can only be connected to a mobile number." |
| Discord | VoIP, burner and landline numbers cannot be used for phone verification |
Checked 2026-10-18; see the service pages for sources.
Which line types exist, with examples?
| Line type | Twilio definition | Examples named by Twilio |
|---|---|---|
| mobile | "A mobile number that generally can receive SMS messages." | Numbers on mobile carriers' SIM cards |
| fixedVoip | "A virtual phone number associated with a physical device." | "For example, Comcast or Vonage." |
| nonFixedVoip | "A virtual phone number obtained online without requiring a physical device." | "For example, Google Voice or Enflick." |
Twilio Lookup documentation, read on 2026-10-18.
A service that wants mobile numbers usually blocks nonFixedVoip first, because such numbers can be created online in seconds. Some also block fixedVoip and landlines.
Why do services distrust phone codes on VoIP numbers?
Because SMS codes are a common target. Microsoft writes that "SMS-based authentication is now a leading source of fraud" and is phasing SMS out for personal accounts. NIST classes phone-based verification as "restricted" and asks verifiers to weigh signals such as "SIM change, number porting". A number that needs no SIM at all is the easiest to obtain, so it is the first one refused.
What can I use instead, and what does it cost?
| Option | Line type | Price | Keeps the number |
|---|---|---|---|
| Your own mobile | mobile | Your plan | Yes |
| Single-use number at RealSIM Numbers | mobile (SIM) | $0.36 (Google) to $1.12 (WhatsApp), US | No |
| 30-day US rental at RealSIM Numbers | mobile (SIM) | $3.60 (one service) | 30 days |
| 30-day US line at TextVerified | mobile (SIM, per its FAQ) | $4.80 (WhatsApp line) | 30 days |
Prices as of 2026-10-18; TextVerified figure from its own page. The median public price of a US WhatsApp code was $1.50 across six providers that day.
A number on a SIM card: your own mobile, a second prepaid SIM, or a SIM-based number from a provider. For a one-off code, a single-use non-VoIP number is enough; for repeated logins, a rental keeps the same number.
Get a SIM-based US number
From $0.36 per code.
Frequently asked questions
Is TextNow a VoIP number?
Yes. TextNow numbers come from Enflick, which Twilio cites with Google Voice as an example of non-fixed VoIP.
Sources
- Twilio Lookup: Line Type Intelligence (checked 2026-10-18)
- Microsoft Support: SMS codes for personal accounts (checked 2026-10-18)
- NIST SP 800-63B rev. 4 (checked 2026-10-18)
- TextVerified: WhatsApp service page (checked 2026-10-18)
- OpenAI Help: VoIP and Google Voice numbers (checked 2026-10-18)
- Microsoft Support: VoIP numbers (checked 2026-10-18)
- Telegram FAQ (checked 2026-10-18)