When you see "phone number unavailable" during registration, the problem is usually that the country code is wrong or the phone number format is entered incorrectly. Check the items below in order to fix most cases.
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Step 1: Check whether the country code is correct
This is the most common cause. For a Mainland China phone number (starting with 13, 15, or 18), the country code dropdown in front of the phone number field must be set to +86 (China). Many pages show a different code by default (such as +1 or +852). If you do not change it, the system may think your phone number location does not match your registration region and report it as unavailable.
What to do: On the registration page, find the flag icon or country code dropdown before the phone number field, then search for "86" or "China" and select +86.
Done when: The country code shows +86, and only then do you enter the phone number.
Step 2: Confirm the country/region of residence option
Besides the phone country code, the registration page also has a separate country/region of residence option. This is different from the phone number location. It decides which compliance terms apply to you.
- If you are a Mainland China ID holder, choose "China" here.
- If you choose another region (such as Hong Kong or Singapore) but enter a Chinese phone number, the system may block registration because the information is inconsistent.
Done when: The country/region of residence matches the actual issuing place of your ID and does not conflict.
Step 3: Enter only plain digits in the phone number field
When entering the phone number, only enter the 11-digit number itself. Do not add +86, do not add parentheses, and do not add spaces. If the system says "invalid format" or "unavailable", the phone number format is likely the problem.
Done when: The phone number field shows only 11 digits with no extra symbols.
Step 4: Check whether the phone number itself is allowed
A few basic rules also need to be confirmed:
- One phone number can only register one OKX account, so it cannot be used repeatedly.
- The phone number must be under your own name and able to receive SMS normally.
- The phone number bound to a sub-account cannot be the same as the main account.
Done when: You have confirmed the phone number you are using has not been registered on another OKX account.
Step 5: If all the above are correct, it may be a network environment issue
If the +86 country code, China residence, and phone number format are all correct but the system still reports an error, your current network environment may have triggered a restriction:
- Is your VPN on? If the VPN node is in a restricted area, OKX may block the SMS channel for Mainland China phone numbers. Check OKX's official list of unsupported service regions; some countries/regions do not support services at all.
- Tip: Turn off the VPN and reopen the app or website using local mobile data (4G/5G). A local IP plus a China country code is the cleanest combination.
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How to verify after troubleshooting
After checking the steps above, try to register again. If the page can send a verification SMS, the phone number has passed. If it still says unavailable, try signing up with an email first and then binding your phone number, or contact OKX official support through the web live chat or the in-app bot transfer to a human.
