The UK’s five largest operators--Vodafone (NYSE: VOD), Orange, O2, T-Mobile and 3—are announcing today their intention to work together to develop common measurement standards for mobile advertising. The FT reports that networks are also working with the GSM Association, the handset industry trade body, to develop a standardized set of metrics to measure the reach of mobile ads. A recent Jupiter Research study found that advertisers remained unenthused about mobile ads because it is unclear how effective they are and how best to measure them.