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IMS and VoLTE: Why They’re Essential for Global Roaming in 2025
The global phase-out of 2G and 3G networks is forcing a transformation in how operators deliver voice services—especially for roaming users. In this new environment, IMS (IP Multimedia Subsystem) and VoLTE (Voice over LTE) are no longer optional technologies. They have become essential components for ensuring seamless, high-quality roaming experiences in 2025 and beyond.
The End of Legacy: Time for an Upgrade
Historically, roaming voice services relied on circuit-switched fallback over 2G/3G networks. With those networks being retired, many roaming subscribers now face voice service disruptions, including the inability to make emergency calls in some destinations.
To overcome this, mobile operators are accelerating their adoption of IMS and VoLTE for international roaming.
IMS: The Foundation for Interoperability
IMS offers a flexible and scalable architecture for delivering IP-based voice, video, messaging, and more. For global roaming, it enables:
- VoLTE roaming across LTE networks
- Interworking with VoNR (Voice over New Radio) in 5G SA
- Support for WiFi Calling (VoWiFi) and advanced features like emergency services
In 2025, IMS is the glue that connects diverse networks and ensures service continuity across borders.
VoLTE Roaming: A Must in 2025 — and Growing
With 2G/3G gone, VoLTE roaming has become a necessity, not a nice-to-have. Operators are now implementing standardized roaming models such as S8 Home Routing (S8HR) and Local Breakout (LBO), making bilateral agreements and certification efforts more common. However, the path is not without friction—interoperability issues, complex testing procedures, and lengthy negotiations continue to challenge global rollout.
Yet, the momentum is clear. Around the world, regional adoption trends are accelerating this shift. Europe and Asia-Pacific are leading the charge with robust VoLTE roaming implementations. Meanwhile, Latin America and Africa are catching up quickly, supported by regional initiatives and infrastructure investments. Even MVNOs and private networks are beginning to embrace IMS and VoLTE to offer consistent voice services across borders.
Beyond Voice: Enabling QoS and Intelligence
As adoption expands, the value of IMS goes far beyond voice. It enables end-to-end Quality of Service (QoS) enforcement—crucial for delivering consistent call quality when roaming. It also integrates with policy control functions (PCRF/PCF) and enables operators to gather meaningful analytics to monitor user experience and service performance in real time.
In this way, IMS becomes not only a platform for voice continuity, but also a strategic asset for network intelligence and customer satisfaction in a competitive global market.
The Future: Interworking with 5G Voice
Although 5G Standalone (SA) and Voice over New Radio (VoNR) are gaining traction, VoLTE remains essential for fallback and interworking across non-5G areas. IMS is the common foundation that allows:
- Smooth transition between LTE and 5G voice
- WiFi calling integration
- Sustainable evolution of the voice core
Conclusion
IMS and VoLTE are not just modern technologies—they are the new global standard for mobile voice services. In 2025, enabling global roaming without them is simply not viable.
Operators who invest in a modular, interoperable IMS core and accelerate VoLTE roaming adoption will gain a significant edge in delivering a consistent, high-quality experience to their subscribers—no matter where in the world they travel.
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