While SMS interoperability is limited to bi-lateral interworking / roaming agreements between operators, it is unlikely that full international SMS reach will be achieved by setting up more and more agreements, which are time-consuming and costly to put in place.
In addition to that, the revenue benefits of an extra interworking connection might not justify the investment required to set it up in the first place.
Outside this frame of main roaming agreements that generate the majority of international traffic for voice and messaging, it makes sense for mobile operators to allocate SMS traffic that belongs to non-connected destinations to an SMS hub.
Mobile subscribers also take advantage of an enlarged SMS reach, being able to send and receive message to all countries and networks.
The hub concept follows this trend, removing a costly and complex area of technical interface and replacing it with a more efficient and effective outsourced solution.