Can not verify by phone number in Vietnam

Welcome to the community!

Vietnam appears on OpenAI’s supported countries/territories lists, so this may not simply be a country-availability issue.

However, the post does not say which verification flow this is for. If it’s ChatGPT, API/platform, community account or something else and the exact error message is not included.

Since this seems to be phone-number/carrier verification, OpenAI Support would need to check it directly. I recommend you to contact them through Help and it may help to include the product/flow where verification failed, the exact error message, country, carrier, number format used and whether SMS or WhatsApp was tried.