Do you really need Google services for your daily activities? No, you don't. Because with Ubuntu you have the right replacement for whatever Google Service you may be using. In the case of Google Voice the answer in Ubuntu is Skype.
Skype is free software (as in beer) which lets you chat with your friends, call mobile phones, landlines and even send SMS. It is an extremely popular software and it can count on a community of several million users. In other words, Skype is the most common and popular software in this segment, and outperforms Google Voice on almost everything.
Google Voice is, in fact, the answer of Mountain View to the growing popularity of Skype. With a few cons. Because, for example, there is no way to contact most of the people you may know using Google Voice, as it is not as common as Skype and also because, for example, European users are still not able to purchase credit and call mobiles or landlines.
Prices for Skype calls are extremely competitive, at least if compared with prices provided by your operator, and typing SMS with the help of a fully-featured keyboard can surely be a plus. Skype is also available for almost every platform around, including Android and iOS, so that you will be able to always have access to your account and contacts, taking advantage of the extremely cheap rates offered by Skype even while you are on the move.
Same with SMS, with Skype able to send text message to and from any place on earth, a must-have for those having close contacts with friends, colleagues or customers abroad. Sadly, Skype is not free as in speech and you have to agree with the typical proprietary software EULA before being able to use it. It can be downloaded for free, but you won't be able to modify, redistribute, or take a look at the code.
In newer versions of Ubuntu you can find Skype in the Ubuntu Software Center available for installation. Skype can also be downloaded from the official website, where the developers provide several different packages able to fit any flavor of Ubuntu.