Tried to download Talkatone on our old iPhone 3G but it would not download, said that iOS 4.3 or higher was required. The latest iOS for the 3G is 4.2, so it looks like no Talkatone on this phone. Is there any alternative that, like Talkatone, allows free calls to be made via GV?
You might be able to find a SIP client, but SIP isn't directly supported by Google Voice so you'd need to read about how to use SIP with Google Voice. It's a more complicated setup to configure, but it works.
That would only be for calls. For voicemail and texting, go to the Google Voice mobile site and tell Safari to bookmark it to the homescreen.
Someone else may know a better alternative, but that's what I can think of. You should try searching the app store for Google Voice to see what comes up.
OK folks, I got it working. I got a SIP phone number from Callcentric. I found a free SIP client app that works with the 4.2, it is called Zoiper. I configured Zoiper to work with my Callcentric number (make sure to disable every codecs except u-law). Then I configured GV to forward calls to my Callcentric number. It works fine.
3CX Phone also works on iOS 4.2 with GV, but it seems this app will not run in the background on an iPhone 3. Zoiper does run in the background if this feature is checked. However, if you want to use this system for incoming calls, you would have to remember to start the app every time you reboot. Or is there some way to make it start automatically on startup?
Did the iPhone 3G support Apple's implementation of pseudo-multitasking? I don't think it did, but I don't know for sure. If it doesn't, the only way to multitask would be to add jailbreak-style multitasking. There might be a tweak in Cydia to launch an individual app on startup.
Don't expect great performance on such an old phone. If cost is the concern, you might want to think about saving for a used or refurbished midrange Android phone from 2010 or 2011, off-contract. You can find them for $100 or less. If you do that, look for something that runs at least ICS (Android 4.0 "Ice Cream Sandwich") because that version was a significant improvement. Or maybe an iPhone 4, but that's probably more expensive and is unlikely to get iOS 7.
Discovered too late a much easier way to accomplish this, no SIP needed. With a jailbroken iPhone 3G, just download an old version of Talkatone, for example version 1.2.3 from http://filetrip.net/dl?PgWA1pzCEi
Then install the app with iFunbox.
With an iPhone 5 you can just download the latest version of Talkatone from the App Store, it is free and it works great. Call anywhere in USA and Canada for free without using your cell phone minutes.