Whatsapp unknown call problems

Some people are having trouble with WhatsApp unknown calls.
How to solve this problem
‪@vestechinfo4407‬

[@royalwritings5369]

Good Brother..Keep up the good work

[@vestechinfo4407]

Thank you

[@alwaysyellaiah]

Tq so much for your information sir..

[@todaycoming8135]

Sir Meru Scoseti ki Kavala

[@vestechinfo4407]

Thank You

[@sharmilakondru0412]

Good Information 👍👍

[@prcomputers836]

Thank you madam, antha Mee support

[@subburoy5853]

Nice sir...good information 👍

[@prcomputers836]

Thank you