Badge-holders have demonstrated a solid understanding of the co-existence of IMS and circuit-switched voice services within the same network, including access domain and service domain selection. They understand the logic and processes involved in delivering a call via LTE or CS access, and the way in which the call is managed (by the IMS or the CS domain). They can explain why SRVCC may be required to maintain a voice call, the handover options, and the required architecture and procedures.