Mobile providers are a thing of the past. With the proliferation of Wi-Fi networks and VOIP services, a carrier isn't needed anymore to make calls. When my Sprint contract expired, I decided to hack a cheaper plan by using an old pre-paid cell phone, a FreedomPop hotspot, and a tablet to make calls and send text messages.

I'm not alone here. In fact, almost a fifth of smart phone users in the U.S. and Europe don't have a data plan, according to the Wall Street Journal. Instead of relying on mobile broadband, smart phone users rely on Wi-Fi.

After looking more closely at the study mentioned by the Journal, I found that here in the U.S., it is normal for carriers to require a data plan with every smart phone. When I spoke to the sales desk of Verizon, T-Mobile, Sprint and AT&T, they said it was industry standard to require a data plan with every smart phone. Often you can buy the phone with no plan commitment, but you end up paying hundreds of dollars for the phone.

If you don't mind changing your existing number, here's how to hack the system so you can make calls without committing to a data plan.

First, buy a new telephone number from Skype. A Skype number runs $18 every three months plus either a Skype credit ($10 increments), or a U.S. and Canada unlimited calling plan ($2.99/month), which makes the total phone bill $9.99 a month.

Skype apps are available on all the major platforms. For me, the iPad version of the app crashed a number of times while trying to answer calls; this is obviously a problem.

In order to send and receive text messages you must buy credit from Skype, and every sent and received message is $0.112. That's not a lot, but I send hundreds of text messages every month and $0.112 does add up quickly.

As far as sound quality goes, Skype's call and video still sounds like voice over IP service, but I didn't have to repeat myself. Besides sounding like I'm speaking in a room with an echo, the quality isn't bad.

In many ways, the best alternative I found was Google Voice. For starters, it's free. It also comes with a phone number and you can even port an existing number to it for $20. But Google Voice has even more limits than Skype. It's available in the U.S. only. Additionally, the service needs to connect to a second phone (like a Skype number), or open Google Chat session (in Gmail) in order to make an outgoing call.

In other words, when you initiate a call on a computer you first choose a phone from which to make the call. This phone can be Google Talk, but for that to work there must be an open Gmail session. If you choose another phone, such as a desk or cell phone set up in your Google Voice settings, then Google Voice calls that number, You answer that call and hear the phone ringing the number you told Google Voice to call. If this sounds awkward and inconvenient then you understand it perfectly.

The Google Voice app can't directly make calls using a Google Chat session on a mobile device; instead you have to tell it to call from your cell phone's carrier plan -- but, of course, the point of all this is to ditch your carrier plan. I managed to locate third-party apps that allow calls directly from mobile devices, including Talkatone (free, but with ads).

On Android GrooVe IP delivers a fully functional Voice account. GrooVe IP costs $4.99 for the full version. There is also a free Lite version with ads and some features missing. On iOS there's iGVoice ($4.99) and the above-mentioned Talkatone, that allow calls.

If the third-party apps disappear, it's not really a big deal. It's easy to go the Skype route as discussed above, and get Google Voice to ring the Skype number. You can set Google Voice can ring multiple numbers of yours at once on incoming calls to your Google Voice number.

In addition to letting you port an existing number, Google's Voice product has several advantages. It offers a voicemail service that transcribes incoming voice mails, and sends the transcriptions to you in email. The transcriptions are often comically bad, but you also get a control to play back the audio of the message. It has unlimited calling in the U.S. and Canada, and competitive overseas pricing. Finally, it offers unlimited SMS messaging, which can be a way around the SMS costs in Skype.

Google Voice's quality was better than Skype when I used Google Chat to call. It has a Web-based interface -- SMS messaging with a full keyboard is a real pleasure -- as well as apps for iPhone and Android.

Once the question of provider has been settled, there is the issue Wi-Fi availability. I spend 95% of my time at my office or at home -- both with Wi-Fi. So that wasn't much of a problem for me. Plus it's so easy nowadays to find hotspots that I never ran into trouble. Of course, I live in San Francisco, one of the most wired spots in the U.S.

My only concern for Wi-Fi accessibility was when I was on the road. When I was testing the phone, I didn't need emergency or roadside assistance, but I see some downsides here. This is a really important point.

Make no mistake, like all of the VOIP providers say in their terms and conditions -- it's not a replacement for an emergency phone. I dialed 911 from Skype and Voice, and in both cases it didn't work. So now I carry a pre-paid phone with me.

I found that a prepaid plan with an unlocked phone works with Google Voice. It's easy to set up Google Voice to also ring that number (along with Skype, and any others like a land line), as well as deliver SMS messages to it. Skype can forward calls when you're offline, but it can't deliver SMS messages.

To circumvent situations where Wi-Fi isn't available, FreedomPop is a reasonable solution. FreedomPop offers 4G data for no cost. So, for a $99 refundable deposit, it's possible to send or receive SMS messages for free, and make voice calls without Wi-Fi. Check the coverage map, as their territory is limited.

You don't even really need a phone -- a tablet, laptop or any Wi-fi device that has Bluetooth and a Bluetooth ear gadget will basically give you a cordless phone.

Knowing what I know now, I closed my mobile account and ported my number to Google Voice. I haven't tested FreedomPop yet. As I said, I'm also carrying a prepaid phone, just in case of emergency. It does mean that I'll likely carry three devices on the road -- an old pre-paid cell phone, the FreedomPop hotspot, and a tablet -- but I think the extra gear is worth it considering I get to wave goodbye to my $100-a-month mobile bill.