They purchased Grand Central like 10 years ago and never killed it.
Grand Central -> Google Voice -> Project Fi.
My biggest gripe with Fi is that there is no way to check voicemail or handle SMS through the web interface. That was the most useful aspect of Voice for me.
"Once you do this, your text messages and voicemail will sync across Hangouts everywhere, including: Gmail chat, Google+ Page or profile, Chrome desktop app, Android or iOS device, Inbox by Gmail, or the Chrome extension."
- You need a cellular data or Wi-Fi connection to send and receive text messages, even on your Project Fi phone
- You will no longer receive SMS messages in your default SMS app, instead you will receive SMS and voicemail in Hangouts on the web and all of your devices
On the plus side, you almost never pay for data roaming charges. Even when abroad.
https://support.google.com/fi/answer/6079398
However, it's not guaranteed:
"Google Voice’s number availability changes regularly, so even if your number was previously on Google Voice, it can’t always be transferred back. If you’d like to keep this number, we recommend transferring it to another carrier that supports it."