Biller following up with clients and potential clients

My wife is the clinician and works at her physical practice in Boise. I am her husband and take care of the billing. I work from our home which is not at the same office location. Sometimes I need to contact clients about billing, appointments and for other reasons. My wife is concerned that if I contact these clients, it's some some of Hippa violation. How do other practices handle this and is there anything in Hippa that says that a person, other than the clinician, can communicate with clients?