Newbie Questions about Grafana Oncall?

Hi, I have a few questions about Grafana Oncall.

  1. Is Oncall a replacement for Prometheus Alertmanager or can it be used downstream from an alertmanager instance ?

  2. Can oncall send SMS messages without using an external service like Twilio ? For example , in my company we can send email-to-sms with a simple email. This can also be done from the linux command line. Is oncall able to send email-to-sms ?

  3. Can we query Oncall from a script to get which entity/person is currenlty oncall ?

  4. Does Oncall have LDAP or SSO integration ?

thanks in advance