A device configured to initiate a voice call in a mobile communication network, the device comprising: a network interface that is adapted to communicatively couple the device to the mobile communication network; a processor; and a memory containing instructions executable by the processor to cause the device to: detect that a user device performs a call attempt of initiating a voice call over the mobile communication network while being wirelessly connected to a WiFi access point; determine at least one call attempt parameter indicative of a situation and/or environment in which the call attempt is performed; decide, based on a decision criterion, whether the voice call to be initiated shall be forced to be used for training a prediction model; if it is decided that the voice call shall be forced to be used for training the prediction model: - initiate the voice call over the WiFi access point as a Voice over WiFi, VoWiFi, call, - derive at least one key performance indicator, KPI, from the performed voice call, and - provide the at least one call attempt parameter and the at least one KPI to the prediction model for training the prediction model; and if it is decided that the voice call shall not be forced to be used for training the prediction model: - decide, based on the at least one call attempt parameter and by applying the prediction model, whether the voice call shall be performed over the WiFi access point or over a 3rd Generation Partnership Project, 3GPP, radio access network. a network interface that is adapted to communicatively couple the device to the mobile communication network; a processor; and a memory containing instructions executable by the processor to cause the device to: detect that a user device performs a call attempt of initiating a voice call over the mobile communication network while being wirelessly connected to a WiFi access point; determine at least one call attempt parameter indicative of a situation and/or environment in which the call attempt is performed; decide, based on a decision criterion, whether the voice call to be initiated shall be forced to be used for training a prediction model; if it is decided that the voice call shall be forced to be used for training the prediction model: - initiate the voice call over the WiFi access point as a Voice over WiFi, VoWiFi, call, - derive at least one key performance indicator, KPI, from the performed voice call, and - provide the at least one call attempt parameter and the at least one KPI to the prediction model for training the prediction model; and if it is decided that the voice call shall not be forced to be used for training the prediction model: - decide, based on the at least one call attempt parameter and by applying the prediction model, whether the voice call shall be performed over the WiFi access point or over a 3rd Generation Partnership Project, 3GPP, radio access network. detect that a user device performs a call attempt of initiating a voice call over the mobile communication network while being wirelessly connected to a WiFi access point; determine at least one call attempt parameter indicative of a situation and/or environment in which the call attempt is performed; decide, based on a decision criterion, whether the voice call to be initiated shall be forced to be used for training a prediction model; if it is decided that the voice call shall be forced to be used for training the prediction model: - initiate the voice call over the WiFi access point as a Voice over WiFi, VoWiFi, call, - derive at least one key performance indicator, KPI, from the performed voice call, and - provide the at least one call attempt parameter and the at least one KPI to the prediction model for training the prediction model; and - initiate the voice call over the WiFi access point as a Voice over WiFi, VoWiFi, call, - derive at least one key performance indicator, KPI, from the performed voice call, and - provide the at least one call attempt parameter and the at least one KPI to the prediction model for training the prediction model; and if it is decided that the voice call shall not be forced to be used for training the prediction model: - decide, based on the at least one call attempt parameter and by applying the prediction model, whether the voice call shall be performed over the WiFi access point or over a 3rd Generation Partnership Project, 3GPP, radio access network. - decide, based on the at least one call attempt parameter and by applying the prediction model, whether the voice call shall be performed over the WiFi access point or over a 3rd Generation Partnership Project, 3GPP, radio access network.