The uptake of data services on mobile phones continues to be very disappointing. SMS remains the most important mobile data application despite the availability of highly sophisticated phones, affordable data connections, and a wide range of software applications and services. MMS failed spectacularly. E-mail has seen some popularity on Blackberry-style enterprise devices, but has yet to be embraced by the mass market. Mobile web-browsing is still a very marginal application, plagued by user interface issues. At the same time, mobile operators continue to invest in expensive mobile broadband infrastructure such as 3G and HSDPA without seeing any immediate return on investment. Exacerbating this, voice revenue continues to decline.