Why Cell May Die in a Modern Hacker's World
by Ron Overdrive
0x00: Preamble
As we move forward with technology, it's becoming quite clear that we're turning into a wireless society.
One would think that perhaps cell phone technology would excel as king of the digital airwaves but, surprisingly enough, 802.11 technologies are becoming more and more advanced, providing faster speeds and longer ranges than ever before.
In urban and suburban areas, you would be hard pressed not to find 802.11 Wi-Fi signals while wardriving, relaxing at the mall with friends, passing through an airport, or staying at a hotel.
For those of us who live in densely populated areas, it's everywhere. For the most part, it's the same deal for cell phones. With portable devices such as netbook computers, iPod Touches, iPhones, Android phones, and other smartphones, it is possible to access the Internet easily with a Wi-Fi connection if you have a poor cell signal or are roaming.
For some of us, this opens up the door to a lot of savings, considering some devices like the Nexus One cost roughly $500 without service and around $200 plus $60+ a month with service. What I'm going to do here is tell you how to completely end expensive service fees legally and have those devices pay themselves off instead of taking a chunk out of your wallet.
0x01: Disclaimer
Before I continue, let me state the legality of this method is dependent on what Wi-Fi locations you use.
I take no responsibility if you're using a residential, unsecured Wi-Fi router and you get caught. I highly recommend this be done using public, free Wi-Fi connections (such as you find in restaurants, hotels, and airports), Wi-Fi networks under the control of your ISP, or secure Wi-Fi connections you have legal access to.
0x02: Pre-Reqs
Let's start off with what you will need for this to work. You will need the following:
- A Google Voice account.
- A SIP account with a call-in number.
- A SIP softphone app.
If you don't already have a Google Voice number, you can easily search around for Voice invites on Twitter or other social networking services.
If your SIP provider only provides SIP2SIP support, you can get a call-in number attached via IPKall.
Various free softphones can be found easily online. Since I mostly use Mac OS X, I use Blink. For the iPhone/iPod Touch there is an app called iSIP, and Android devices can use SIPdroid. Android devices will also want to have the Google Voice app installed while iPhone/iPod Touches will want the iPhone Edition Google Voice page bookmarked.
0x03: Setup
Now on to the setup process.
First, sign up with Google Voice, sign up for a SIP service (I use iptel.org), register a call-in number for your SIP account, and install your softphone app.
Be sure to read the how-to guide on your SIP provider's site on how to configure your softphone. For the most part, you usually just enter your username, password, and SIP domain. Now go into Google Voice and choose your Voice number; then add your SIP call-in number as your primary phone number. When you click "verify" you should get a call on your SIP app. Just dial the verification number and you're set.
Note: Android users should make sure their Google Voice app is configured to force all calls through Google Voice.
0x04: Usage
Incoming calls should be a no brainer; give out your Google Voice number as your phone number.
When people call, they will be greeted by the Google Voice system and forwarded to you or to your voicemail, if you're not online. Outgoing calls are simplest on Android devices; you simply dial out and the Google Voice app should intercept your call.
On the iPhone/iPod Touch, and portable computers, you will need to visit the Google Voice website where you simply click the call button and enter a number or name of the contact you wish to call (the SIP account should already be selected as the callback number).
Google Voice will call your SIP account and then call the person you are trying to call, bridging the two calls together.
Finally, SMS (text messaging) can be done using the Android app or through the Google Voice website.
0x05: Flaws and Final Thoughts
There's no such thing as a perfect solution and this is no different.
While this offers great potential for saving money, there are a few flaws. First and foremost, one depends on a usable Wi-Fi connection. While some may see this as a huge factor, it's actually insignificant.
After all, that's what voicemail is for, which we all use on our cell phones anyway for the same reason: for one reason or another we are unavailable.
Then there's the fact that outgoing calls and SMS can be a little more involved. Google is already working on this.
Recently, they purchased Gizmo5 and they are planning on merging it with Google Voice, so the methods described may shortly become deprecated, if Google plays their cards right. Also, there are security concerns over using public Wi-Fi connections that do not have AP isolation enabled, as any good hacker with working knowledge of the SIP protocol could potentially sniff your packets and listen in to your phone calls.
Much like regular cell phones, and even hard lines, you always have to assume the line is insecure and not share any sensitive information. If you are willing to pay a small yearly fee for in and out calls, Skype is always a good alternative to using Google Voice and SIP. There are Skype clients for all platforms and Skype has the benefit of some encryption.
Just remember, you get what you pay for.