This number is for Care credit, it is a credit card for medical expenses. The phone call with this number is from an automated service to confirm recent activity on the card. This is to help protect the account of the person who has the card.
If the're going to call - then they should at least leave a voice mail message if you don't answer the phone. THAT would be more about CUSTOMER SERVICe and protecting the accounts of the people with the card.