Can a customer be converted to an agent / collaborator?

[Pedro Cora]

Yes, as long as you have 'space' on the Agent License, you just need to click on Add Agent.

For more details, take a look at the documentation at https://confluence.atlassian.com/display/SERVICEDESK/Managing+agents

UPDATE:

To see a customer on the Agent screen, you first need to edit the user and make sure he's in the JIRA Users Global Permission.

-- Pedro

[Dave Ferguson]

This appears to not work.  The add agent screen won't find any user that is a service desk customer. 

[Pedro Cora]

My bad, before you do that, you need to ensure that the Customer belongs to the groups that can access JIRA

[Dave Ferguson]

Still no dice. Any user marked in admin / user management as a "SD" user is not able to be found at all. I am unable to add those users to any group in Jira nor can I grant them Jira application access.