Call recordings are forwarded to you via email and appear in Google Voice's list of voice mail recordings. You can generally tell the difference between voice mail messages and recorded conversations because the latter are probably longer, and say "Transcription not available."
While this may seem a bit archaic compared to Visual Voicemails, it is still better than nothing. It may take a bit longer to listen to your voicemails, and you won’t have as much control over them as you would on a Visual Voicemail service, but is better than missing the call entirely.

iPhone recorder apps only work because they utilize 3-way conference calls, either incoming or outgoing. The third "caller" is a recording line, provided by a service from the app's developer. Obviously, 3-way calling is a must-have feature of your iPhone for this to work, so be sure your carrier supports it. In the US, the big three all do, but some smaller carriers do not—at least not in a way these apps support.
I know you’re thinking what does recording an iPhone call have to do with voicemail, but it turns out that a simple trick allows you to use the service to record any phone call, and it works great. Not only will you get the recorded phone call, but you’ll be able to save and share the call recording as an audio file as well.