Well if u r testing the conditions under which GC occur. Last time it happened was 4 days ago, in the morning the usual quest of finding the mobile and called through my land line number. The call was going though but phone wasn't ringing. I eventually found it. I called again but the same result the interesting part was that as i was holding the phone when I was calling I can hear the noise which happens on landline phones when a cell phone is near by on call but my phone was silent. My verdict the baseband was working but the rest of OS was not able to detect and ring the phone (I guess thats what GC is ). After a few retry I restarted the phone and the phone started working normally. I was on v20b the first it happened on it since release. I switched to v20g yet to falter.