Google Voice is another great, free resource for educators from Google. It provides a phone number that teachers can use as a contact point for students and parents. I like having a separate number to use for school.

There are some very cool features too:

Voicemail transcription - it will transcribe a voicemail into text and send it to you via email, SMS, or on the web.
Access - you can access it through your own phone or online. There are apps for pretty much every smartphone around. There is also a mobile app available for use on a mobile browser.
You can also port other phone numbers to your Google Voice number to make things simple.
You can have different voicemail greetings for different people and numbers.
You can screen callers.
You can conference call.
You can have the Google Voice calls ring to any other phone.
You can even call people from inside Gmail!
And more.

I love the ability to have a phone number and voice mail that I can give my students and parents so that they can contact me at any time.

Check it out.