Methods and Apparatuses for Determining and Selecting Internet Protocol Multimedia Subsystem, IMS, Media Functions in a Wireless Communications Network

A method performed by a second Core Network, CN, node (152) for determining Internet Protocol Multimedia Subsystem, IMS, media function candidates to an IMS call session for a User Equipment, UE, (120) in a wireless communications network (100), the method comprising:

• obtaining (602) correlations, which correlations relate to geographical locations between the IMS media functions (160) and UPF nodes (140), regarding their mutual distances,
• receiving (603) information and a request from an IMS control node (130), which information is about a User Plane Function, UPF, node (140), and its geographical location, which UPF node (140) is serving the UE (120), and which request requests IMS media function candidates operating at distances closest to the geographical location of the UPF node (140),
• determining (604) IMS media function candidates according to the request, based on the obtained correlations and the received information, and
• sending (605) to the IMS control node (130), the determined IMS media function candidates.

A second Core Network, CN, node (152) configured to determine Internet Protocol Multimedia Subsystem, IMS, media function candidates to an IMS call session for a User Equipment, UE, (120) in a wireless communications network (100), wherein the second CN node (152) further is configured to:

• obtain correlations, which correlations are adapted to relate to geographical locations between the IMS media functions (160) and UPF nodes (140), regarding their mutual distances,
• receive information and a request from an IMS control node (130), which information is adapted to be about a User Plane Function, UPF, node (140), and its geographical location, which UPF node (140) is serving the UE (120), and which request is adapted to request IMS media function candidates operating at distances closest to the geographical location of the UPF node (140),
• determine IMS media function candidates according to the request, based on the obtained correlations and the received information, and
• send the determined IMS media function candidates to the IMS control node (130).