I don't know if this sheds any light on the problem, but this happens to me 100% of the time when I use GV to call specific phone systems (hospital, medical office, help desk, etc.), usually when the call is put on hold or transferred, but also sometimes when my call is answered.
I have an Obi 202 with 3.2.2 (Build: 8680EX) software, Anveo on SP1, and GV on SP2.
The static does not happen when my call is made from SP1/Anveo.