SIP Endpoint SDK session statuses

Can anybody please explain what the SessionStatus.Alerting is in SIP Endpoint SDK? The manual has no explanation for it.

I’m migrating from Windows RTC and am looking for the equivalent of RTC_SESSION_STATE.RTCSS_INCOMING and RTC_SESSION_STATE.RTCSS_ANSWERING but they don’t seem to exist in the SIP Endpoint SDK. Can these statuses be detected some other way?

I would look on MediaOffer for INCOMING and MediaAccepted for ANSWERING