Can the ENC Mobile US SIM receive Codex, Grok and Apple ID codes? A full guide to the T-Mobile physical SIM (2026)
Short answer: this SIM solves the "no overseas texts in China" step, but no SIM can guarantee every service will send you a code. The ENC Mobile US T-Mobile physical SIM is a real +1 mobile number, not a VoIP number, $28 shipped to China, and it receives US texts once you connect to Wi-Fi and turn on Wi-Fi Calling. It meets OpenAI's no-VoIP rule for Codex, matches the +1 country code Grok's sign-up page shows by default, and can serve as a trusted phone number for Apple Account two-factor authentication. Whether a service sends a code or accepts the number is decided by its own rules and your IP environment.
On this page
- 1. Short answer: service by service
- 2. The 3 usual blockers for overseas codes in China
- 3. What ENC Mobile is
- 4. Codex: phone verification at sign-in
- 5. Grok / Grok Bot: +1 is preselected
- 6. Apple ID: a trusted phone number for two-factor authentication
- 7. 4 things to do before requesting a code
- 8. What this SIM cannot fix
- 9. FAQ
- 10. Related guides
Most people searching for the ENC SIM want one thing: to receive a verification code for Codex, Grok or an Apple ID while in China. Below we explain what the SIM is, then go service by service: whether it works, how to enter the number and what it cannot fix.
Service rules reflect official pages available on 17 October 2026; SIM details follow LarkSIM's product information. Rules change, so follow the page you see on the day.
Short answer: service by service
| Service | When it asks for a number | Can ENC be used? | What to watch |
|---|---|---|---|
| Codex (OpenAI) | Codex sign-in may require phone verification with a one-time code by SMS or WhatsApp | The number type qualifies: OpenAI rejects VoIP numbers, and ENC is a T-Mobile mobile number | Mainland China is not on OpenAI's list of supported countries and territories; a number does not change that |
| Grok / Grok Bot | Sign-up or sign-in may show "Verify your phone number" with +1 preselected | Yes: ENC is a +1 US mobile number; enter the 10 digits | xAI does not publish which number types it accepts; xAI decides whether to send a code |
| Apple ID (Apple Account) | Two-factor authentication needs at least one trusted phone number that can receive codes | Yes: ENC receives texts and calls | The account's country or region setting, not the phone number, makes it a US account; if the number is cancelled, it stops working as a trusted number |
The 3 usual blockers for overseas codes in China
- check_circleNo overseas number: many overseas services do not accept a +86 number or do not deliver codes to it.
- check_circleThe number is treated as virtual: OpenAI's help centre says it does not support landlines, VoIP (including Google Voice) or premium numbers.
- check_circleTexts do not reach China: many US SIMs have no roaming signal in China, so texts never arrive while you are away from the US.
ENC addresses all three: it is a US +1 number, a T-Mobile mobile number rather than VoIP, and in China it receives texts over Wi-Fi Calling. The condition is that your phone can turn on Wi-Fi Calling.
| Option | Number type | Who controls the number | OpenAI accepts this type? | Best for |
|---|---|---|---|---|
| SMS-receiving websites | Varies | Not you; it may belong to someone else by the next sign-in or recovery | Uncertain | Unimportant one-off sign-ups |
| Google Voice | VoIP | Your Google account | No, OpenAI names it as unsupported | Not suitable for Codex |
| ENC US T-Mobile physical SIM | T-Mobile mobile number | You, as long as you renew | The type qualifies | Codex, Grok, Apple ID trusted number |
| giffgaff UK SIM | UK mobile number | You | The type qualifies | When a US number is not required; long-term use in China risks disconnection |
What ENC Mobile is
ENC Mobile is a US mobile carrier aimed mainly at Chinese-speaking residents and students in the US, running on the T-Mobile network. It has Chinese and English websites and offers English, Mandarin and Cantonese support plus a China support line. "ENC SIM" and its Chinese brand name 迎客 refer to its SIM cards.
Prices quoted online differ because there are two kinds of SIM: ENC's direct SIMs, with main plans from $10 a month, and channel SIMs sold and topped up by resellers, with a small plan included for the first month. LarkSIM sells the channel SIM:
| Item | Details |
|---|---|
| Network and number | T-Mobile network, US +1 mobile number, physical SIM, not VoIP |
| Price | $28 (about ¥199), first-month plan included, shipped to an address in China |
| First-month plan | 30 minutes of US calls + 100 US texts, no data |
| Phones | iPhone 6S or later, Chinese or international model, unlocked; not jailbroken or SIM-adapter phones |
| Use in China | Connect to Wi-Fi and turn on Wi-Fi Calling; no signal after inserting it is normal; the first activation needs an overseas network environment |
| Number | Randomly assigned, possibly previously used, cannot be chosen or changed |
| Renewal | No self-service top-up; support tops up; ¥66–99 a month depending on the activation ZIP code's tax; cancelled after 30 days suspended |
| After-sales | Special item, cannot be returned or exchanged once shipped |
If you need a number that receives US texts in China, Buy the US T-Mobile physical SIM (ENC); $28 (about ¥199) including the first-month plan, shipped to China.
Codex: phone verification at sign-in
Since June 2026, several users have reported in OpenAI's official openai/codex GitHub repository that ChatGPT signs in normally, but signing in to Codex redirects to a phone verification page on auth.openai.com that requires a one-time code by SMS or WhatsApp before Codex can be used.
On number types, the OpenAI help centre says landlines, VoIP (including Google Voice) and premium numbers are not supported, and phone verification is completed by SMS. ENC is a T-Mobile mobile number, so the type qualifies.
- 1
Confirm ordinary texts arrive
Connect to Wi-Fi, wait for the Wi-Fi Calling indicator, then send a text to the ENC number from another phone. - 2
Choose the US and enter 10 digits
On the verification page choose United States (+1) and enter the 10-digit US number without repeating +1. - 3
Request once and wait
Wait a few minutes after submitting. Repeated requests get limited; users on GitHub report a "too many phone verification requests" message.
Grok / Grok Bot: +1 is preselected
According to xAI's documentation, Grok Bot has no separate login; it uses the shared xAI sign-in, which may show Grok or xAI branding. Some users see this phone verification page during sign-up:
- check_circle+1 preselected: the country code for the US and Canada. ENC is a +1 US number, so keep +1 and enter the 10 digits.
- check_circle"You must have a valid mobile number": the page wants a real mobile number that can receive texts; ENC is a T-Mobile mobile number.
- check_circle"SMS charges may apply": refers to possible carrier charges. ENC's first-month plan includes 100 texts.
- check_circlexAI does not publish which number types it accepts; xAI's account and risk rules decide whether a code is sent.
For signing up to Grok with a UK number, see the Grok bot overseas SMS verification guide.
Apple ID: a trusted phone number for two-factor authentication
According to Apple, you create an Apple Account with an email address, setting your country or region and two-factor authentication along the way. Two-factor authentication needs at least one trusted phone number to receive codes, which can arrive by text message or phone call.
- check_circleWhat ENC does: serves as a trusted phone number and receives Apple's text or call codes while on Wi-Fi.
- check_circleIt does not set the region: the account's country or region setting decides that, not the phone number. A US number does not make a US account.
- check_circleCheck filters first: if you filter Unknown Senders in Messages, Apple says to look there for the code.
4 things to do before requesting a code
- 1
Turn on Wi-Fi Calling
Insert the SIM, connect to Wi-Fi, turn on Wi-Fi Calling and wait 3–5 minutes for the indicator. If it fails, follow the 7 troubleshooting steps for an ENC SIM with no signal. - 2
Test an ordinary text
Send a text from another phone. If ordinary texts do not arrive, fix the network first instead of requesting codes repeatedly. - 3
Request once per service
Wait a few minutes after submitting the number. Repeated requests invalidate earlier codes and can trigger limits. - 4
Add backup verification
Add at least one of an authenticator app, a passkey or a backup email so important accounts do not depend on this number alone.
What this SIM cannot fix
- check_circleRegion policies: a phone number does not change a service's rules about where it is available.
- check_circleWhether a code is sent: that depends on the service's rules and your IP environment; no number can guarantee it.
- check_circleNumber history: numbers are random and may have been used before; a service may say the number is already in use, and the carrier does not change numbers.
- check_circleTexts away from Wi-Fi: in China this SIM works only over Wi-Fi Calling.
- check_circleBulk sign-ups: for your own accounts only; not for bulk registration or any unlawful use.
FAQ
Can the ENC SIM receive Codex verification codes?expand_more
Grok asks for a phone number. Will ENC work?expand_more
Can I register a US Apple ID with an ENC number?expand_more
Ordinary texts arrive but a code does not. Is the SIM faulty?expand_more
Can I receive codes without Wi-Fi?expand_more
How is ENC different from SMS-receiving websites?expand_more
What happens to linked accounts if the number is cancelled?expand_more
Can I use ENC for codes on Android?expand_more
Real +1 number · T-Mobile network · Card checked before dispatch
US T-Mobile physical SIM (ENC)
A real US +1 mobile number, not VoIP, delivered as a physical SIM to your address in China. Check the current price, Wi-Fi Calling and keep-number notes on the product page before ordering.