Question about adding a contact

Good afternoon, my clients are law firms. I add contacts simply to know who I am communicating with, and I need to add only the full name and position. But if I add only the full name and position, then I write an error "There must be at least one contact (phone, email, skype, jabber, whatsapp)" But sometimes I just don’t know the contact’s additional phones or mails, because I communicate with him through the company’s landline phone, and the company’s general mail. If you register the same city number as in the company, the program will generate a duplicate error. I don't want to remove the checkbox to allow duplicating companies. Can I somehow remove the obligation to fill in the phone and mail? Or how else can this problem be solved?