According to a report in Providers.by site MTS Belarus completed "the implementation of a DPI platform, which has already been successfully tested and put into commercial operation. This technology allows to distinguish different types of traffic (VoIP, torrent, HTTP-traffic, etc.) and set priorities for them, and even a separate tariff .. The company says that is all data traffic passes through the platform DPI .. In the long term may apply differentiated policies for various types of information: using the platform can allocate traffic is Skype, ICQ, certain sites (eg, VKontakte and classmates). Accordingly, we can offer competitive rates for access to these sites and applications" (based on Google translation).
Sounds very similar to what KPN was planning to do before being hit by Net Neutrality.
It seems that DPI is also used to offer a "Turbo Button" service removes connection speed and volume limits.
See "МТС может расширить линейку мобильных анлимов" - here.