It's not the official fix promised by Google, but it should resolve the problem. The fix is courtesy of the Android forum at MoDaCo. You need your bootloader to be unlocked -- and more importantly, to understand what "your bootloader needs to be unlocked" means.
Doing that's not against the rules -- several manufacturers of Android phones offer official unlocking tools -- but it will void your warranty.
When you're ready, follow the instructions at MoDaCo, and the problem should be resolved. But be warned: you risk bricking your phone and we strongly recommend you wait for the official fix from Google and Samsung, which should be along shortly.
The volume bug causes the volume to suddenly drop to nothing, in the middle of calls or while playing music, and causing you to miss the phone ringing. It's caused by the 900MHz 2G phone signal frequency used by O2 and Vodafone. Orange and T-Mobile use the 1,800MHz 2G frequency and Three uses 2,100MHz, and evidence suggests they're unaffected.
The volume problem is annoying, as the Nexus is otherwise a great phone. We can't recommend it yet, but as soon as the volume problem is resolved we'll adjust our review accordingly.
Are you affected by the volume bug? Are you willing to try this fix? Let us know how you get on in the comments or on our Facebook page. If you're torn about buying a Galaxy Nexus, here's how it shapes up against the iPhone 4S and Nokia Lumia 800.