Instruct: Classify the given Amazon review as either positive or negative.
Query: v710 alone provides better call quality than HF600

You're probably better off with just a car adapter to power the phone and a technique to attach the phone to the dash so that it doesn't roll around on something like a car seat. The v710 provides best speakerphone quality to both ends if used alone.I also tried to control the speaker volume from the phone (there's nothing on the speaker unit to do that), and wasn't satisfied.