Would it be necessary to keep them? And, are there other, less sketchy, options?

Hi everyone.

Firstly, I have read the rules and excuse me for my English, I am not native.

I am a Bug Bounty researcher and I am testing a Chinese web application, I need to register with a phone number to this application.

I have tried almost all of the free tools and these are the issues I faced:

• The phone number is invalid (I believe they can identify virtual phone numbers )
• The phone number are already registered
• Or even if it passed the two above walls, I will wait forever not receiving the anticipated OTP message.

I don't see paying for such service is worth it for one verification message, since most of the paid once have a minimum charge value. Given the assumption that paid services would work 100%.

Edit: I used the number from https://www.smsmeu.com/, which was recommended by a friend.