We have a BX2000 and 16 Draytek Vigorphone 350's. Sometimes (Maybe 1 in 15 calls at a guess) when an incoming call is transferred to another extension the other extension can hear the external caller, but the external caller hears no audio. They then hang up and redial and usually it works second time round. Has anyone else experienced this?

BX2000 firmware is 3.8.1.5 and Vigorphone 350's are at 12202.26.1.11