Effect of network-based steering on international traffic

Network-based steering is one of the options to redirect the outbound roamers to the preferred partners and works by refusing registration messages from outbound roamers. By its nature, this causes some additional load on international links, which may mean additional cost for international connections. The amount of this additional load depends on several parameters such as the number of outbound roamers or preferred partner coverage performance. Though the exact value might be quite different for each network, an average of more than 5% additional load can be given as an educated estimate. This may mean that network-based steering may increase operators’ international connection costs.

SIM-based steering

Though it looks inevitable to have this additional load on the links, it is possible to reduce this overhead by employing network-based steering only when we have to. In other words, using adaptive SIM-based steering can reduce this overhead. SIM-based steering can be considered as the ultimate solution to steering. It is the best possible way of redirecting subscribers, making the handset work for the operator instead of trying to guess what is happening from the Home Public Land Mobile Network (HPLMN) side.

Using this approach, the handset is forced to pick the preferred partner as long as its service is available. It also makes sure that the handset switches back to the preferred partner even if it had to use an un-preferred partner because of coverage issues. It allows operators to have different levels of preferred partners, not just preferred and un-preferred partners. As operators can trust the handset now, knowing it will camp to a preferred partner if possible, it also allows subscribers to register and start using voice and data services more quickly. Removing the need for network-based steering also removes the overhead on international connections and increases steering performance.

However, most of the benefits of SIM-based steering depend on a specific command called Refresh. Without it, the settings will not be applied before the handset is restarted. Yet this command is not supported by every handset or SIM card profile. It means that the performance of SIM-based steering depends on the distribution of handset models as well as different SIM profiles on the network.

To maximize the benefits of SIM-based steering, it’s therefore vital to plan ahead while making SIM purchases to make sure that the new SIM profiles support this command even though there is no close future plan for SIM-based steering deployment. Even then, operators may still need to employ network-based steering for unsupported handsets as it is not possible to control the distribution of the handsets.

Roaming disabled subscribers

While network-based steering introduces an extra load on international links, it may need to be accepted in certain cases. Where it should definitely not be accepted is when it relates to steering outbound roamers who have their roaming disabled.

The percentage of roaming disabled subscribers who have their handset turned on while they are abroad is relatively high. The exact rate can be quite different for each network, but it can be around 30%. And worse, these handsets generate almost twice more registration messages per unit time, compared to regular subscribers. Based on these numbers, it’s clear that almost half of the registration requests are generated by roaming disabled subscribers. Applying network-based steering on these requests brings us nothing but pointless overhead traffic on international links.

Integrating and configuring the steering system properly is the solution to this problem. The steering system can access the operator’s internal database for this information or query the GSM nodes. Another solution can be to use passive mode solutions with steering on the return path.

While these solutions are to reduce the unnecessary cost of network-based steering, a much better option could be to turn those roaming disabled subscribers into roaming enabled, revenue generating ones.

See also Outbound Roamer Steering and Mobile Data Boost