The market for femtocells was pioneered by a small number of companies who continue to lead the development and evolution of the technology. Often small startups, it can be argued that they created the market, overcoming many hurdles to prove that it was both technically and commercially viable.
This process has given them all deep insight into the detailed operation of a successful femtocell solution. As the market expands, more new vendors will argue that they should also be considered mainstream femtocell access point vendors, so this list is somewhat subjective and likely to change.