Google Voice is intended to be a call forwarding and management service, not simply a free version of a standard VoIP telephone service provider. As such, GV's voice mail is a mandatory part of the service, and it can't be disabled. Google has no reason, nor intention, to change this. GV voice mail will answer calls after approximately 25 seconds of ring time, and this period is not adjustable. If you don't want to use GV voice mail, then your alternative answering device must answer before GV voice mail grabs the call. Otherwise, use a SIP VoIP service provider that offers the flexibility you want, such as Callcentric.