Telecommunication services are offered via networks, such as Public Land Mobile Networks (PLMNs). In some examples, a network can include an access network, a core network, and an Internet Protocol (IP) Multimedia Subsystem (IMS). Other networks can include other components. Services can be provided by a user's home network. When the user is using a non-home network or visited network, that network may have a relation with the user's home network. Some information transmitted by the user's user equipment (UE) is communicated back to the home network via the visited network.
The communication of information from the UE to the home network via the visited network may take different routes, travel through different network elements based on, for example, the type of relation between the home and the visited network, or based on the technology of the networks. For example, a fifth generation (5G) core network has different network elements compared to an Evolved Packet Core (EPC) network. EPC is a framework that provides converged voice and data in a fourth generation (4G) wireless network, such as a Long Term Evolution (LTE) network.
The IMS contains, for example, a P-CSCF. The EPC contains, for example, a Mobility Management Entity (MME). The 5G CN contains, for example, an access and mobility management function (AMF).
Networks may offer a Circuit Switched (CS) domain, where traditionally voice calls and emergency calls are handled, or a Packet Switched (PS) domain, offering PS services including access to the IMS are handled.
The PS domain supports emergency services via the IMS. A UE may support accessing one or both of the CS domain and PS domain. A UE supporting PS domain may also support IMS.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.