My OBi 110's call quality has gone down considerably after one of the recent firmware updates (I'm not sure when -- probably in the past 3 months), and yes, I now have the latest firmware running. I thought it was Google Voice-related, but I'm hearing the same distortion and dropouts on my SP1-configured Callcentric service. Hard to describe in words, but it's like a phase-distortion that comes and goes. Both GV and CC are using G711u codec, and I have a high-quality, low-latency FiOS ISP connection. When the distortion is absent, the CQ is excellent. Service statistics for the last call on SP1 show no packets lost, no overruns, and 121 underruns out of 69126 packets received.
I am going to swap out the OBi with my SPA 2102 to narrow down the issue, but based on other reports in the forum, I think a bug was introduced.