Contact is one of your professional offices. If you have been added by a professional office, you shall see the professional office in "Contacts" tab.
Click "Add Contact" to invite professional. You need to enter the professional's phone number to link with the professional. Once the professional approves you. You will be able to communicate with the professional.
Alternatively, you can scan the professional's QR code in phone, which you will be automatically approved to talk with the professional.