Hi, I was trying to sign up with Bitcoin, but it keeps telling me that my mobile number is invalid? what should I do? thanks
Bitcoin is a decentralized[1] crypto
currency. There is no bitcoin company, bitcoin customer support hotline, bitcoin CEO, etc.
tldr;
No one owns the bitcoin nameIt seems like you're planning on using a service whereas you can buy/sell bitcoin. It would be helpful if you specify what site/app you're using as there's so many of them for us to know specifically which service you need help with. Please edit your post and provide more information.
[1]
https://isr.uci.edu/projects/pace/decentralization.html