Fortunately I have found a solution: Google Voice + Gizmo5 + Sipdroid. Google Voice is a free service which lets it’s users unify all their phones under one number. Simply give friends, family and coworkers that one number, and calls will ring through to whatever phones the user chooses, based upon rules they define. Gizmo5 is a SIP provider that can connect to Google Voice and allow users to make phone calls over the Internet. Gizmo5 has been bought by Google, so registration is currently closed. However, everyone expects that it will eventually be integrated with Google Voice. Finally, Sipdroid is a nice, Open Source SIP client for Android that can connect to services like Gizmo5.

I’ve played with this combination before, when I was using a G1 Android phone from HTC. The reasons I did not stick with it then were because the G1′s battery life was pretty bad, and the G1 struggled enough with performance that it was not feasible to keep Sipdroid running in the background.

Now that I have the amazing Nexus One though, all this has changed. The battery life on the N1 is pretty good by smart phone standards, and it’s performance is high enough that I can easily run Sipdroid in the background all the time without any noticeable performance impact.

I’m using my home WiFi for Sipdroid. I have always been told that WiFi eats battery life rather quickly. However, I’ve been surprised at how much this has not been the case. After a full day of being connected to wireless almost all the time, WiFi only used up about 2% of my phone’s battery (this is with moderate use of the connection). I’ve come to the conclusion that simply having wireless connected does not use much power, but actually transferring data does.

This solution has been working great, but has not been completely without problems. When I receive calls, both parties (the person I talk with and I) have excellent sound quality. However, when I initiate the call via my phone, the person on the receiving end gets tons of latency and a lot of static. I have worked around this issue by initiating the calls via the Google Voice web interface. This hack is slightly annoying, but it is not too bad since I almost always have my laptop on.

After a few days of use, I am quite happy with this solution, and am looking forward to hopefully seeing VOIP kill off traditional telephone providers in the future. AT&T, T-Mobile and others should be very afraid, especially if municipal WiFi becomes more common.

1. Use the package manager of your choice to install ia32-sun-java6-bin.
2. Download the Android SDK for Linux, then extract the zip file.
3. In the SDK tools folder, open up the ddms file in your favorite text editor.
4. Modify line #72 to the following: java_cmd=”/usr/lib/jvm/ia32-java-6-sun/bin/java”

Here are the screenshots I took:

As you can see, I’m running a clone of the theme on HTC’s Hero Android phone. This theme can be downloaded here. All the install took was downloading the theme, putting it on my phone’s SD card as update.zip, booting into recovery mode and flashing the update. Of course, you’ll need a rooted G1 for this to work. I’m running JesusFreke’s wonderful 1.5 build. Read this guide for instructions for rooting your G1.