The BPL OPERA standard is used primarily in Europe by ISPs. In North America it is used in some places (Washington Island, WI, for instance) but is more generally used by electric distribution utilities for smart meters and load management. Since the ratification of the IEEE 1901 (HomePlug) LAN standard and its widespread implementation in mainstream router chipsets, the older BPL standards are not competitive for communication between AC outlets within a building, nor between the building and the transformer where MV meets LV lines. Even higher information rate transmissions over power line use RF through microwave frequencies transmitted via a transverse mode surface wave propagation mechanism that requires only a single conductor. An implementation of this technology is marketed as E-Line. These use microwaves instead of the lower frequency bands, up to 2–20 GHz. While these may interfere with radio astronomy when used outdoors, the advantages of speeds competitive with fibre optic cables without new wiring are likely to outweigh that. These systems claim symmetric and full duplex communication in excess of 1 Gbit/s in each direction. Multiple Wi-Fi channels with simultaneous analog television in the 2.4 and 5.3 GHz unlicensed bands have been demonstrated operating over a single medium voltage line conductor. Because the underlying propagation mode is extremely broadband (in the technical sense), it can operate anywhere in the 20 MHz20 GHz region. Also since it is not restricted to below 80 MHz, as is the case for high-frequency BPL, these systems can avoid the interference issues associated with use of shared spectrum with other licensed or unlicensed services. Two distinctly different sets of standards apply to powerline networking as of early 2010. Within homes, the HomePlug AV and IEEE 1901 standards specify how, globally, existing AC wires should be employed for data purposes. The IEEE 1901 includes HomePlug AV as a baseline technology, so any IEEE 1901 products are fully interoperable with HomePlug AV, HomePlug GreenPHY, and HomePlug AV2. On the other hand, medium-frequency home control devices remain divided, although X10 tends to be dominant. For power grid use, IEEE has approved a low-frequency (≤ 500 kHz) standard called IEEE 1901.2 in 2013. Several competing organizations have developed specifications, including the HomePlug Powerline Alliance, Universal Powerline Association (defunct) and HD-PLC Alliance. On December 2008, the ITU-T adopted Recommendation G.hn/G.9960 as a standard for mobile networks high-speed powerline, coax and phoneline communications.