Software-Defined Radios are the primary technology being used for this, although generally cognitive radio is considered the next step of SDRs. The general idea is to have a radio with the digital smarts to react to the environment rather than just blindly tuning to a frequency.
White space still is not widely understood. The concept is that spectrum can be used opportunistically rather than by walling off frequencies for specific uses. These companies did some of the seminal work in the technology. They are designing radios which sniff the spectrum around them and use frequencies which are not being used locally. Many of the technologies come under the heading of 'cognitive radio'.
This is really a field where not other company has entered, Neul Radio is going to be a better initiator for Machine to Machine communication. Since they are going to use a very wide band which mostly not used completely it will help mobile service providers install their infrastructures at diverse areas.