Sets a broadcast group's access mode and, for a PRIVATE group, each listed team member's access level.

• PUBLIC: every team member can access the group. teamMembers is ignored.
• PRIVATE: only team members with an access level can access the group. Team members are identified by the phone number on their DoubleTick account.

The access mode is always applied. Team members are then updated one by one, and an entry that cannot be applied fails only itself: it is returned in failed with a reason and the rest are still updated. An entry fails when its phone number is invalid or repeated in the request, does not belong to a team member of the organisation, or belongs to a team member whose access level cannot be changed (the group creator, or a team member whose role has the "manage channel access" permission, such as owner or admin, who always has full access).

Requires the "manage channels" permission and the "manage channel access" permission for this group.

Rate limited to 60 requests per minute, per organisation and user.