IMS voice call concurrency handling scenarios

SIM1 status	SIM2 event	SIM2 action
Active call on Wi-Fi (VoWiFi)	Receives IMS call (SIP INVITE) over Wi-Fi	Rejects call with 486 – Busy here
Active call on Wi-Fi (VoWiFi)	Receives IMS call (SIP INVITE) over LTE	Rejects call with 486 – Busy here
Active call on Wi-Fi (VoWiFi)	Receives SMS/MMS on either SIM1 or SIM2	SMS/MMS is accepted/received on corresponding SUB
Active call on Wi-Fi (VoWiFi)	Receives CSFB call over LTE on either SIM1 or SIM2	Drops CS page/call in LTE
Active call on Wi-Fi (VoWiFi)	Receives CS call on GSM/WCDMA on either SIM1 or SIM2	Drops CS page in GSM/WCDMA
Active call on LTE (VoLTE)	Receives IMS call (SIP INVITE) over Wi-Fi	Rejects call with 486 – Busy here