Is the traditional IMS (IP Multimedia Subsystem) fitting into 5G World?

All these years, IMS is predominantly used for delivering Voice & Video based multimedia services over IP networks like VoLTE, VoWiFi, RCS, etc. As IMS is access independent, it can connect to the 5G core as well (via UPF node) for delivering services like Voice over 5G (Vo5G) and even allow roaming features over 5G/LTE networks.

However, with the very specific requirements like support to Cloud-native applications, Virtualized nodes, RESTful APIs, Microservices, Network slicing & so on for the 5G network, traditional IMS nodes need to be virtualized & cloud-ready in order to be integrated into the 5G networks.

Fig. IMS in a Telecom Network

In its current traditional on-premises form, IMS nodes require longer deployment cycles and are relatively non-flexible when it comes to deploying different multimedia services. Also, it uses protocols like SIP & Diameter to communicate within IMS nodes and EPC. 
 

This would not be the case with the 5G network which is based on RESTful APIs and discourages dealing with multiple protocols. With SDN/NFV & Cloud-based deployments, 5G nodes can be developed, deployed, managed, integrated, auto-scaled like Software & Containers; which is not the case with traditional IMS framework.

Therefore, Operators have already started moving their traditional IMS nodes & EPC components towards Virtualized Network Functions.

5G supports a plethora of services around Things, Consumers & Enterprises and rely on SBA, Edge Computing and Network Slicing to manage the required resources, low latency & high throughput for treating different use-cases & segments.

4G Operators who have already upgraded their Core network to Virtualized EPC & Virtualized IMS nodes over Cloud and adopted CUPS feature for separating User & Control planes are in a much comfortable & cost-efficient position to move towards 5G deployments.

They can leverage their existing Cloud-based & fully virtualized networks to implement a 5G network integrated with IMS along with the specific features as mentioned in the article (SBA, Network slicing, Edge Computing, etc.) for enabling FWA, eMBB, URLLC & mMTC use-cases.

Glossary: IMS (IP Multimedia Subsystem), LTE (Long Term Evolution), EPC (Evolved Packet Core), SIP (Session Initiation Protocol), VoLTE (Voice over LTE), VoWiFi (Voice over WiFi), RCS (Rich Communication Services), UPF (User Plane Function), SBA (Service Based Architecture) CUPS (Control & User Plane Separation), FWA (Fixed Wireless Access), eMBB (enhanced Mobile Broadband), URLLC (Ultra-Reliable Low Latency Communications), mMTC (massive Machine Type Communications)