Google Voice is one of their lesser-known tools but I find it invaluable – basically, you can get a free, local phone number that functions as a virtual phone, one that can call out, receive calls, record (and transcribe) voicemail and send/receive texts, all from a browser (or the Android/iOS mobile app).
If you’re considering migrating a Google Voice number, The first thing to be aware of is that, although they’re free for personal Google accounts, it’s a paid add-on for all versions of G Suite for Business ($10 per line per month).
To move an existing number, the first thing to do is to unlock the phone number of your current (free) Google Voice number. You can do that by going to https://www.google.com/voice/b/0/unlock.
Once that’s done, set yourself up with the Google Voice service in your Google Admin console and port the number in according to these instructions.
It’s worth noting that existing text messages and voicemail recordings are not migrated to the new G Suite-based account. In fact, I’m unclear whether or not they are actually deleted once the number is ported out, so best to export the data using Google Takeout before proceeding with the number port.
There seems to be some conflicting information online about this process… here’s an article from Google that suggests that personal Google Voice numbers can’t be ported to G Suite accounts in the first place…