There are many reasons to enjoy Wi-Fi calling, from starting video chats with family far and wide, to giving your old phone a new lease on life as a Wi-Fi-only device in little Johnny's hands. However you want to use it, you still need to know which apps are best.

There are quite a few companies battling it out in the data-calling space, each of which has its own benefits and drawbacks. Some offer voice-only calling, while others allow for video calls, photo transfer, and group chat.

Select apps share the love with other services, but others prefer to keep things in-house. I've spent some time playing with a few of these clients over the last few years and found some to be incredibly useful. Here are five of my favorite apps for making free Wi-Fi calls.

Google Voice

As the most used application on my phone, Google Voice also works well on tablets. I enjoy being able to synchronize my text messages, missed calls, voice mails, and contacts across multiple devices. More importantly, however, I love the fact that I can use the same phone number on any and all devices. This not only means texting on tablets and Web browsers, but calls from any phone with a Wi-Fi connection.

Google

I've been using Google Voice since 2007 when it was still known as Grand Central. I was mostly drawn to the fact that I could use one phone number for my home, work, and cell phone, and fell fast in love with the service. It didn't matter where I was or what phone was nearby, I could be reached at the same number everywhere.

Unfortunately, Google has done very little with Google Voice in the last five years. Perhaps as a result of carriers being unwilling to play ball, the service is good but not great.

Indeed, I am still unable to send and receive picture messages. What's more, it is still only offered in the United States. Small drawbacks aside, I cannot say enough about swapping phones in and out and keeping the same phone number.

It is quite comforting to know that I can resume conversations from phone or tablet and even jump to PC for calls and messages. I'm willing to bet that many of your favorite smartphone bloggers use Google Voice.

Standout features: Number porting; call recording; calls from within Gmail; Do Not Disturb; inexpensive international rates; and computer Web browser extensions.

Fring

One of the features I appreciate the most in Fring is the ability to freely call other Fring users around the world. What's more, it doesn't cost a penny to use video chat or send messages. In cases where you need to call a landline or mobile that's outside your country of origin, the FringOut option provides inexpensive rates.

Fring

Android phones and tablets that feature front-facing cameras can take advantage of video calling with up to four friends at a time. Fring is a great place to start for those looking for a Skype alternative and has improved over time. I have been impressed with the quality in both voice and video calls.

Standout features: Free Fring-to-Fring calling anywhere in the world; inexpensive international rates; up to four video callers at once.

Skype

As the biggest name in Wi-Fi calling, the Skype app for Android has seen more than 100 million installs. Much like the desktop counterpart, the mobile version allows for a variety of ways to stay connected. Most readers are familiar with the free Skype-to-Skype voice and video calls and IMs, all of which translate nicely to Android.

Skype

Skype works quite well on Android phones, especially for those with a front-facing camera. Along those lines, a recent update enables landscape calling for tablets that offer a front-side shooter. Additional details include low-cost calling and SMS to landlines or mobile devices as well as integration with Windows Live Messenger.

I have come to use Skype on Android more than a desktop these last few years and think that the new tablet experience is wonderful. Many of my contacts have Skype accounts, and I appreciate that I can go mobile and still be just a ring away. With more than 600 million Skype users across the globe, it is a safe bet that you know a few as well.

Standout features: Free Skype-to-Skype calling; inexpensive international rates; simple and intuitive interface; massive user base.

KakaoTalk

Much like the others on this list, KakaoTalk allows for free calling and messages within the network. Where things differ, however, comes in the fun and playful user experience that includes animated emoticons and custom themes. I was pleasantly surprised at the number of higher-quality themes and options available, and quite enjoy being able to change things up on occasion.

KakaoTalk

While I didn't have too many contacts using the KakaoTalk network, I noticed that there are more than 50 million Android users. Indeed, the service also works across multiple mobile platforms, including iOS, BlackBerry, and Windows Phone. My instincts tells me that this is one of those fast-growing networks used by a younger demographic, but this isn't necessarily a bad thing.

Additionally, a pair of free plug-ins create a more robust experience, including polls and photo sharing. For what it's worth, the recent 0.8.2 release of KakaoPoll is a bit buggy, so you may want to hold off for now. With that in mind, the developers have been pretty active in updates and bug fixes, so it should not be long.

Standout features: Custom themes; animated emoticons; free calling within KakaoTalk network; plug-in support.

Tango

Another popular cross-platform service, Tango works for desktops as well as other mobile devices. Features include free international voice and video calling as well as messages and photos. Recent updates to the Android include support for sending audio messages, sharing photos to Facebook, and avatars and video filters for calls. Note that some of the features require Android 4.0 and higher to work properly.

Tango

I am also fond of the Tango Surprises, which are animations that work over the top of your text conversations. Designed around specific themes, they are a great way to add flair to an otherwise standard conversation. A quick glimpse through the growing list of packs yields familiar names such as Care Bears, Elmo, and the Pink Panther. Of course, you could also opt for more romantic themes for Valentines Day. Note that these packs cost $1.99 each but include multiple animations.

Other features that add to the Tango experience include the ability to play games from within video calls, and avatars. Because, face it: a cartoon cat looks better than I do in the morning.

Standout features: Free Tango-to-Tango calling anywhere in the world; inexpensive international rates; animation packs; games over video calls.

Your favorites?

Which Android applications are you using for calling over Wi-Fi or data connections? Is it one of the five highlighted here, or do you prefer a different client? I would love to hear your feedback in the comments below.