Do I need a Zendesk Talk license for Text agents?
Yes, any agent who replies using your Text channel needs to have a Talk license. However, you can have a different number of Zendesk Talk or Text and Support agent seats.
This information can be found in the Supplemental terms: Zendesk's service-specific terms of our Master Subscription Agreement.
For more information on Talk billing, see the article: Zendesk Talk billing FAQ.