Without captcha and other security elements this is the way to hell
People are stupid and they will fill text into phone number etc.
So frontend should validate data strongly + similar validation has to be also on backend. Backend can simply connect to CRM database and create new record or call create method with curl. However for curl you have to have valid account in GO which is strictly recommended because you will see who created the record. Second option will be also required with incoming GDPR.
My recommendation - split these data into separate addressbook.
IT Analyst, Independent seasoned Group-Office developer, Educator of web applications