I am trying to pay my subscription, but I get the following error message:
Our credit card processor encountered the following error:  Hold-call. Your credit card has not been charged. Contact email@example.com.
The  Hold-call code error is sent from your card provider. To fix this issue, call the number on the back of your card and have them approve payment to Zendesk.
For more information about code errors, see Resolving issues when your credit card fails.