How I Use It
I use Google Voice as a way to give out a mobile phone number to colleagues, students, and parents, while not having to give out my personal number, nor maintaining two cell phones.
My Google Voice number is tied to my school's GAFE GMail account so I can check texts and calls via my school account.I can initiate and answer calls and texts directly form my inbox (or my iPad) without needing to pull out my personal cell phone. If I want to use my personal cell phone I use the Google Voice iOS app and initiate calls and texts from there. The recipient sees the caller ID as my Google Voice number, not my personal handset number.
Google Voice is a great way to make yourself accessible and available without giving up privacy.
Here is a slide deck I created about Google Voice's benefits for educators:
http://www.slideshare.net/mr_casal/simplek12-webinar-google-voice-041712
My Take
Google Voice is an amazing teaching tool. It isn't so much an in-class teacher tool as it is an extension of the class tool. It allows for follow-up questions from students and parents after class. It also provides a way to stay in touch with parents from your desktop, without using a personal cell phone.
In many schools and distrcits teachers are not allowed to use cell phones in school. This is often a detriment as parents and studnets (middle school and above) often use their cell phones as a primary point of contact. Having a Google Voice number allows you ans the teacher to keep those lines of communication open with district-issued devices, having access to a cell number without needing an actual phone.
Google Voice has been invaluable to me. I freely give out that number knowing I can check it all from my laptop or iPad, and don't have to give out my personal cell phone.
It is also great for teachers who travel between buildings. It gives you a single number you can check from any computer, and the calls can be routed to ring at multiple numbers (if you have multiple offices).
Here is a slide deck I created about Google Voice's benefits for educators:
http://www.slideshare.net/mr_casal/simplek12-webinar-google-voice-041712