We recently heard back from ITTF that, YES, Bluetooth Coaching is now legal under the USATT and ITTF rules.  The Samson Dubina Table Tennis Academy will be moving forward with the idea using it in leagues and tournaments to best prepare our players for the US Nationals in July!  One important point to remember is that communication is only allowed between points and it is NOT allowed during the point.
Video examples and tips about bluetooth coaching will be available soon.
Check back within the next few weeks!