Telenor Sweden leverages NocMap for seamless HLR-migration

Project at a glance

• Migration scope: 6 million+ SIM cards

• Migration time per HLR: ~14 hours

• Critical safeguards: Real-time user monitoring & instant roll-back capability

• Outcome: New HLR live with no customer impact

About Telenor Sweden

Telenor Sweden is a telecommunications provider whose network covers 99 % of the Swedish population and serves more than 2.5 million mobile customers. It is part of the larger Telenor Group, a leading mobile-carrier operator across Scandinavia, Central Eastern Europe and Asia.

The Challenge

As part of a core network modernisation project, Telenor Sweden needed to consolidate two legacy HLR systems into a single new register. The migration was undertaken in a live customer environment, including more than six million SIM cards — with the requirement of keeping disruption to an absolute minimum. Such an undertaking in a live network environment has been likened to “open-heart surgery” on the core infrastructure.

A key risk in any HLR migration is user drop-off, where subscribers unexpectedly fall out of the network. Even minor drops can create significant customer-visible issues, making real-time visibility absolutely essential.

Such an undertaking in a live network environment has been likened to “open-heart surgery” on the core infrastructure.

Why NocMap made the difference

For a HLR migration of this scale it was vital to monitor service performance in real-time. Using Subtonomy NocMap, Telenor Sweden’s engineering team monitored key KPIs such as real-time number of registered users (to instantly spot any drop-offs),

success and failure rates, and location update volumes. This allowed them to detect any signalling storms or device related anomalies, especially important during large-scale moves of SIM cards and network registration.

NocMap provided full visibility, enabling the engineering team to confirm that subscriber counts stayed stable throughout the process. This was especially critical during the migration waves, when millions of SIM cards were moving from the old HLRs to the new system.

The engineering team used large-screen NocMap Graphs dashboards during the live operation. This gave them the confidence that if anything looked incorrect for even a moment, they could instantly trigger a roll-back to protect the user experience.

As Magnus Johansson, Mobile core at Telenor put it: “We are very happy with the outcome of this HLR migration which did take lots of preparation. For a big project like this you always expect some minor glitches which in our case turned out to be some old IoT devices that didn’t understand they needed to do a location update, but other than that, it was done very seamless without impacting our customers. Using NocMap for monitoring during the migration was of great help for us. For a critical project like this, you cannot afford to wait several minutes to see if something goes wrong and NocMap lets us see all graphs in real-time and had something happened we would have been able to just click in the graph to get directed to the source of the issue immediately.”

As Magnus Johansson, Telenor says:

“We are very happy with the outcome … For a critical project like this, you cannot afford to wait several minutes to see if something goes wrong – and NocMap let us see all graphs in real-time …”

Results

The two HLRs were migrated in two phases, 14 days apart. Each migration took around 14 hours and was executed over a weekend when traffic levels were lowest. Thanks to real-time visibility and the ability to initiate an immediate roll-back if needed, the migration was completed successfully with no customer-visible disruption and the new HLR fully operational.

What it means for telecom operators

This migration illustrates how live visibility into subscriber behaviour, network KPIs, and registration stability is essential when executing complex core changes. With NocMap, operators can confidently:

• Mitigate user drop-off risks

• Detect issues instantly

• Safeguard customer experience during large-scale transformations

• Execute migrations with a proven safety net for roll-back