From what I understand of your first paragraph, you'd like a specific agent (or group of agents) to have the "Support Department" title within the Sales Department? Is this correct? Or is your first paragraph saying that you'd like his signature to switch from Sales to Support as needed? 

 

When creating signatures, you can also customize per agent by using Custom Fields. Rather than copy the steps here, please take a look at this KB article where we explain how this is done: Use Custom Fields in Ticket Signatures. Essentially what you'll do is create a custom field for, let's say, Job Title. In your signature, you can then choose your custom field as a variable. Make sure each agent has the custom field filled in and their custom title (or phone number, department, etc.) will show in that space. If the agent doesn't have the custom field completed in their settings, the line where the custom field is entered will be left blank. 

 

Hope this is what you're looking for!