Over-the-top (OTT) messaging providers such as Viber, WhatsApp and Line are commanding an increasing share of mobile users' messaging traffic, cutting into operators' SMS revenues. They are also rushing to expand their offerings to include movies, books and, in some cases, voice calling services. In response, European wireless operators are seeking ways to partner with OTT messaging providers, while also hedging their bets by pursuing their own OTT strategies. What operators should be doing depends on which part of the industry one is speaking with. Check out carriers' complicated strategies in this FierceWirelessEurope special report.