Final answer:
To add an activity to an existing ticket after receiving an inbound call, you can add a note or comment, update the status or priority of the ticket, and document any relevant information about the call.
Step-by-step explanation:
When you receive an inbound call about an existing ticket, you can add a note or comment to the ticket to document the call and any relevant information. This helps maintain a complete history of the ticket and allows other team members to understand the context of the call and any actions taken. Additionally, you may update the status or priority of the ticket based on the information received during the call.