Mitakuuluu says "Signing in failed!" after sending the same message to about 20 contacts and 6 groups. Maybe they banned me? How can I know wich is the exact problem?

For identification I use a number that I don't have anymore, so I couldn't re-register. Anyone have any idea or could help? If I cannot continue using that number, I won't give them my real number, so probably I won't use anymore whatsapp.