GrandCentral was awesome for giving you 1 number which forwards to as many other phones as you want. Since Google acquired GC, it’s been getting better everyday.
NOW you can setup any phone number (including your existing phone numbers) with Google Voice and your voicemail experience will be revolutionized. Every time somebody leaves you a voicemail you will receive an email that includes not only transcribed voicemail, but also gives you ability to listen to the message right in your email. Of course, you can still listen to all voicemails by calling your Google Voice number.
Some would say it’s a bit “big brother’ish” to have all your voicemails analyzed and transcribed by Google but I love it! Makes voicemail much more accessible, convenient and simple. I LOVE YOU GOOGLE! Keep doing what you’re doing.