In order for any speakerphone to work it needs to stop the feedback from the
speaker to the microphone.  This problem is not present in a handset because the
speaker is right next to your ear, so the speaker output is very low.  Most
speakerphones solve the feedback problem by turning off the microphone while
keeping the speaker output enabled.  This breaks the feedback loop.  It also means
that you cannot interrupt the other person because the microphone output is
disabled.  We feel that being able to interrupt is crucial in any quality
conversation. Without it most people are frustrated and feel that the conversation is
not natural.

Our speakerphone solves the feedback problem a different way.  It uses a special
algorithm to take the speaker sound out of the microphone output so that it keeps
the microphone on.  You can interrupt at any time.  This produces natural life-like
conversations.   Not only can you interrupt, but you can talk over the other party while
still hearing them.  We call this Tru-Talk.

Tru-Talk can only be achieved by using one of the most powerful DSP’s available to
run the patented feedback cancellation algorithms.  The feedback cancellation
algorithms were developed at Utah State University by Dr. Jacob Gunther.  SP
Communications licensed these algorithm for use in the Tru-Talk SP-1rH.
TRU-TALK
SP Communications
Creators of the Tru-Talk Personal Speakerphone