A method comprising: receiving notification that a handover is required from a packet switched network to a circuit switched network while an internet protocol multimedia subsystem session is ongoing; characterized by: receiving an indication that an eCall session is active in the internet protocol multimedia subsystem session; determining that media gateway resources in the circuit switched network, including an eCall session codec, are required to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session; and causing the media gateway resources, including the eCall session codec, to be reserved in the circuit switched network to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session, wherein receiving the indication comprises receiving the indication that the eCall session is active in the internet protocol multimedia subsystem session that was previously provided via Gx and Gxx reference points by extending a packet switched-to-circuit switched-session-continuity attribute value pair to indicate that a service data flow supports the eCall session and is a candidate for packet switched to circuit switched continuity. receiving notification that a handover is required from a packet switched network to a circuit switched network while an internet protocol multimedia subsystem session is ongoing; characterized by: receiving an indication that an eCall session is active in the internet protocol multimedia subsystem session; determining that media gateway resources in the circuit switched network, including an eCall session codec, are required to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session; and causing the media gateway resources, including the eCall session codec, to be reserved in the circuit switched network to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session, receiving an indication that an eCall session is active in the internet protocol multimedia subsystem session; determining that media gateway resources in the circuit switched network, including an eCall session codec, are required to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session; and causing the media gateway resources, including the eCall session codec, to be reserved in the circuit switched network to support the eCall session, as supplemented by a minimum set of emergency related data, that is active in the internet protocol multimedia subsystem session, wherein receiving the indication comprises receiving the indication that the eCall session is active in the internet protocol multimedia subsystem session that was previously provided via Gx and Gxx reference points by extending a packet switched-to-circuit switched-session-continuity attribute value pair to indicate that a service data flow supports the eCall session and is a candidate for packet switched to circuit switched continuity.