This is pretty much what I did, then just tied it to the Nexus S's using the Sipdroid app
How to make and receive free calls over the internet using Android
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Here are the steps.
1) Sign up for Google Voice. If you buy the phone, you'll get an invite.
2) Get a free SIP account here:
https://secure.dns-hosting.info/register_sip_account.phtml
You'll end up with a SIP phone number, something like this:
2223334444@sip2sip.info.
You'll need your password again for step 4.
3) Get a free IPKall phone number here:
http://phone.ipkall.com/
You'll be asked for your SIP info. Enter it like this:
SIP Phone Number: 2223334444
SIP Proxy: sip2sip.info
Remember your IPKall number, because you'll need it for step 6.
4) Get a free PBX account at
https://www4.pbxes.com/index_e.php. My pbx username is "ctrager", which I'll be using for step 5.
a) Add an extension - use "100" for the extension and remember the password.
b Add a trunk. You'll use your SIP info again.
c) Add an inbound route
d) Add an outbound route
The screenshots below show you how to do the configuration. I don't know what anything means. If by chance I've screwed up with these screenshots, see the guide that I followed:
There are also screenshots at
[GUIDE] SIPdroid & Google Voice setup (updated 3-12-2010) - xda-developers
5) On your phone, download sipdroid. Go to "Settings", "SIP Account Settings" and enter the following:
Authorization Username: ctrager-100 <-- this is your pbx username and your pbx extension
Password: Your pbx extension password.
6) You should now be able to receive incoming calls to your IPKall number. Add it as one of your phones on Google Voice. If all goes well, your Android device will ring, like a real phone. But, me, I had trouble getting Google to accept the confirmation number I was typing. I tried using this too, holding the phone up to the computer speaker:
F r e e U K - FreeUK Broadband -. I can't remember which worked, the tone generator applet or my phone itself, but after several tries it worked.
You're done. So, now, if somebody calls your Google Voice number, it will ring your IPKall number, and then your SIP account, and I think then to your PBX account, and then via sipdroid, your phone will ring. To make an outgoing call, use the Android browser to go to Google Voice, call the number from the web page, and Google Voice will first call you back to make the connection.
I used Dolphin Browser to make a custom bookmark straight to Google Voice then put those icons on the first screen so I can just use that like an app to initiate a call.
