Hi Michal,
If we're talking about GUI, check Configuration - Services - Guest Management. There you can configure SMS and E-mail policy for captive portal. Afterwards, this policy is applicable in 'Services' within device profile.
![aa97ba431a83436ea0427c661b56e021_01b4b832-3a3e-4122-88b3-9bfa8623b046.png aa97ba431a83436ea0427c661b56e021_01b4b832-3a3e-4122-88b3-9bfa8623b046.png](/t5/image/serverpage/image-id/5812iD250606C57BDD505/image-size/large?v=v2&px=999)
Hope that helps,
Tomasz