How to refer to User Grants in Identity Provider from On-CallRosters in Allarming

I need to set an alarm notification and I want to create some On-CallRosters with specific users present in the ‘User Grants’ list in Identity Provider.
When I try to manage users in On-CallRosters, on the gateway web page, I can only choose registered users in ‘Users, Roles’ in Security section. Is it possible to add the users present in Identity Provider without repeat the contact?

No, on-call rosters pre-date Identity Providers. On-call rosters are associated with user source profiles, so you must add your user and their contact info (i.e. email / phone) to one of your user source profiles in order to add the user to the on-call roster.