ABI Research is now tracking 28 commercial LTE networks, and the firm said the biggest concern at this point for carriers is a shortage of available spectrum. "Regulators in certain countries have not yet announced any plans for LTE spectrum allocation," said ABI research analyst Fei Feng Seet. Countries such as Taiwan won't be ready for LTE spectrum auctions in the near future because the 700 MHz and 2.6 GHz bands--the bands most suitable for LTE--are not clear. Article