The step that stops the most people from getting ChatGPT, Codex and Claude fully working is SMS verification. OpenAI relaxed the phone step for basic ChatGPT signup in 2026, but you still need a supported-country number to create an OpenAI API key, to re-verify from a new device, and for Claude — so a working number is still essential. Your +852 number is not in OpenAI’s or Anthropic’s supported-country lists, and free VoIP numbers (Google Voice, TextNow, TextFree, Skype) are actively blocked. What you need is a non-VoIP number from a country both services accept — and you can get one cheaply, without real-name registration, from a provider you can sign up to from abroad. This guide covers every practical route.
What ChatGPT and Claude actually require
- A number from a supported country — US, UK, Canada, Australia, Japan, Singapore, Germany, France and many more all work for both services.
- Not VoIP — virtual/over-the-internet numbers are rejected.
- Not already flagged — numbers that many people have already used for signups are blocked.
- Reachable later — both services may ask you to re-verify from a new device, so you want a number you can still access for a while.
The three ways to get a number
| Option | Best for | Typical cost | Real-name needed? |
|---|---|---|---|
| Virtual-number services (5sim, sms-activate) | One-off signup, cheapest | From ~US$0.01–1 per number | No |
| Real US numbers (TextVerified) | Reliable verification, keep the line | US$0.25+ per code; rentals US$1.50+ | No |
| UK/US eSIM with a number (Lycamobile, Tello) | Long-term 2FA, you own the number | ~£3.50–5 or ~US$5 per month | No (UK prepaid); some US providers want an address |
Option 1 — Virtual-number services (fastest, cheapest)
Services like 5sim, sms-activate.org, Teleram and HeroSMS rent you a phone number for minutes, then show the incoming SMS on their website or app. They cover hundreds of countries and explicitly list OpenAI/ChatGPT (and similar services) as a category you can buy a number for. You register with just an email — no real name, no ID — and top up with a card or cryptocurrency. Prices start at a few cents.
How to use 5sim (as an example)
- Create an account at 5sim.net (email only) and add a small balance — US$2–5 is plenty for one or two verifications.
- Pick the service: select “OpenAI/ChatGPT” (Claude is sometimes listed as Anthropic; if not, an OpenAI number usually still works for Claude).
- Pick a country — start with UK, US or Canada — and look at the success-rate stats; pick an operator with a high rate.
- Buy the number, paste it into the ChatGPT/Claude signup, and read the code that appears on the 5sim page.
Option 2 — Real US numbers (most reliable per-use)
TextVerified is the name to know when a virtual number fails. Its numbers are real, non-VoIP US lines backed by physical SIMs, which is exactly what the strictest services — Google, PayPal — look for. You buy a verification for a specific service, or rent a number you keep. There is no real-name registration: sign up, buy credits with a card or cryptocurrency (Bitcoin, Ethereum, Litecoin, USDC, Tether, Monero), and use a number.
- One-off verification: from about US$0.25 per SMS/voice code.
- Short rental: 1–14 days, from about US$1.50, unlimited SMS on the line.
- Renewable rental: about US$5/month to keep the same number permanently — ideal for re-verification and 2FA.
- Choose a US area code, and get a refund if the code does not arrive.
The trade-off: you pay a bit more, but a fresh US line has a much lower chance of being flagged — which is worth more than the money when you are signing up to an account you will pay for monthly.
Option 3 — A real eSIM with a foreign number (best long-term)
For a number you actually own and can receive texts on for years, buy a prepaid eSIM that includes a phone number — not just data — in a supported country, ordered online from Hong Kong.
UK numbers (+44) — Lycamobile, Lebara, giffgaff, Three
UK prepaid SIMs do not require real-name registration, and the operators sell eSIMs online that are delivered by email/QR code — so you can buy one from Hong Kong and get a UK number without showing ID. Lycamobile UK’s eSIM plans start around £3.50–£5 for 30 days with a UK number; Lebara runs promos from about £2.50/month.
US numbers (+1) — Tello, US Mobile
Tello sells prepaid eSIMs with a real US number from about US$5/month; US Mobile’s cheapest “Light Plan” is about US$8/month. The catch: some US providers want a US billing address or a US-issued card, so check the checkout before you commit. US numbers are the single most compatible choice for both ChatGPT and Claude.
Which country should you pick?
| Country | ChatGPT | Claude | Ease of getting a number |
|---|---|---|---|
| United States (+1) | Yes | Yes | Easy — many services and eSIMs |
| United Kingdom (+44) | Yes | Yes | Easy — no real-name prepaid eSIMs |
| Canada (+1) | Yes | Yes | Medium — fewer cheap options |
| Australia (+61) | Yes | Yes | Medium |
| Japan / Singapore | Yes | Yes | Harder — fewer anonymous cheap lines |
| Germany / France (+49 / +33) | Yes | Yes | Medium — eSIMs exist but pricier |
US and UK numbers are the sweet spot: both services accept them, they are the cheapest to obtain anonymously, and their lines are the most likely to pass the non-VoIP check.
How much it costs to keep a number (for the odd SMS)
If your real goal is simply to hold onto a number you can receive the occasional verification SMS on, the cost picture is very different from the one-off services above. Some options are free to keep, others cost a few pounds or dollars a month. Prices verified August 2026 — always re-check, because this market changes quickly.
| Provider | Setup | Keep cost (occasional SMS) | Incoming SMS | Notes |
|---|---|---|---|---|
| giffgaff (UK PAYG eSIM) | ~£0–2 (eSIM) | £0 — any use once every 6 months | Free | ⚠️ July 2026 mass bans for long-term overseas use |
| Lycamobile UK (eSIM) | from ~£3.50 (first-month promo) | £3.50–5 / month | Free | 30-day bundles with a UK number |
| Lebara UK (eSIM) | from ~£2.50 (3-month promo) | ~£2.50–5 / month | Free | Promo pricing ends after 3 months |
| Three UK (PAYG eSIM) | ~£10 one-time top-up | £0 — 1 chargeable activity per 180 days | Free | 35p/min, 15p/text, 10p/MB |
| Tello (US eSIM) | from ~US$5 | ~US$5 / month | Free | Cheapest US line for keeping |
| US Mobile (US eSIM) | ~US$8 | ~US$8 / month (Light Plan) | Free | 2GB + unlimited talk & text |
| TextVerified rental (US) | ~US$1.50 / 1–14 days | ~US$5 / month (renewable) | Free | Real non-VoIP US line, keep forever |
| 5sim / sms-activate (virtual) | ~US$0.05–1 per number | n/a — single-use | one-time | Cheapest one-off, but no keepable line |
Making the number last
- Do not register dozens of accounts on one number — reused numbers get flagged and can pull your ChatGPT/Claude account down with them.
- Keep the number reachable for at least a few weeks after signup — you may be asked to re-verify.
- For a long-term line, pick the UK/US eSIM or a renewable rental and keep it topped up.
- Match the number’s country to your VPN country at signup for a natural-looking account.
Frequently asked questions
Can I use my Hong Kong (+852) number with a VPN?
No. The VPN changes your IP address, but the phone number is still checked against the supported-country list, and +852 is not on it. You need a number from a supported country.
Can I use a free number from Google Voice, TextNow or TextFree?
No. Those are VoIP numbers, and both OpenAI and Anthropic block VoIP numbers for verification. This is the most common failed-attempt mistake.
Will ChatGPT or Claude ban me for using an SMS verification service?
The risk is not the service itself — it is the number. Numbers that have been widely used for other accounts are flagged and refused. A freshly provisioned number, especially a real carrier line, is usually fine. Reusing one number for many accounts is what attracts attention.
What if the verification SMS never arrives?
Cancel or return the number and try another — most services auto-refund if no code arrives. Use the success-rate statistics that 5sim and sms-activate display per country and operator, and prefer US/UK lines.
Do I need to keep the number after signup?
For at least a few weeks. Both services can ask you to re-verify by SMS when you sign in from a new device or location. A cheap UK/US eSIM you keep topped up, or a renewable rental, is the safe way to stay re-verifiable.
Does ChatGPT still need SMS verification at signup?
OpenAI removed the mandatory phone step for new ChatGPT accounts in 2026 — email is usually enough to register. You still need a supported-country number to create your first OpenAI API key, to re-verify when logging in from a new device, and for Claude signups.