The spec of my Jiayu G3 is discussed in the last post. A few days into it, I figured out many superior features that Android phones can do while the iPhone 5 can't.
My G3 is untappable! One weakness of Voip is encryption. Propriety systems like Skype can easily add encryption. Google Chat (Talk/Voice) don't have encryption, at least true as of last year. SIP client like Sipdroid don't have it.
Sipdroid uses a PBX service (like a telephone exchange) that provide VPN. But they charge for it. Then there is an Openvpn related service who sells pay-as-you-go bandwidth. This could be very attractive in comparison to my $6 a month service. But then they don't support Linux so I have to pay extra on top of my desktop. Then I discovered that their is the general Openvpn client. About 5 sec into the app description, I realized that Android being Linux, I can use my existing Openvpn files from my service. Indeed I just need to drop those key files into the microSDHC card and then file up Openvpn client without hassle. You can turn it on and off just like any apps with a switch. And there's a "key" indicator when connected. Even better than the client on my desktop.
So whatever on my phone will be in a secure tunnel all the way to any of the Kryptotel servers. From then it's unencrypted to the PBX, which interface with the telephone network. Nobody can wiretap me like a telephone line. They have to locate the service that I'm using, and the PBX I'm using, and then monitoring all the traffic. It should not be easy to find out which connection is mine. And then the servers and PBXes can be changed easily if needed be. Of course end to end encryption you can simply use Skype.
BTW, you need to get a microSDHC card for the G3 or else many functions cannot be performed, such as the camera and many clients that need storage! And without the card, you may think that the USB doesn't work at all other than charging. Android dropped the old USB drive connection in favor of Media device protocol. Other phones maintain the compatibility with or without a SD card. The G3 implementation is simpler. You don't see any storage from USB unless you have a SD card.
One more thing. Sipdroid do not do sms / text, which is rather strange. It used to have or may have, video too, but they took it out or haven't put them back in yet. But the Sipdroid quality is super for free. Once setup, you can use *43 for echoing test. Basically they send you back your own voice once they received it. I was worrying that it's too much. But for less than 80 ms, it's like playing echo with a kid. You tell them to repeat whatever you say face to face.
Google Voice can do text absolutely free that I always know and use. But it's tricky without a sim card or with a disable sim. GV setup always assume you have a working phone. I also worry about multiple logins that will ruin the xmpp to sip protocol conversion. At the end, I can send and receive text using the GV app. There is an app to integrate that with the native messenger, but tricky without a in service sim card.
As long as Google Voice is free, you don't need to pay anything. If all else fails and go bust, you can always run your own telephone exchange. The most popular PBX is Asterisk, which can be run on the $30 Raspberry Pi. I'm surprised that there is no Asterisk server running on Android, which is a lot more powerful than the Pi at 700 MHz. Most Android phones are dual core and >1GHz.
Of course I want to stream any of my media collection and any other things to my phone, say if I am in the bathroom.
The standard is DLNA. There are apps for your Android which acts as a server, client, and controller. So you can control whatever goes wherever, TV, computer, phones, even in your bathroom. Apple has it's own standard. You can do the same if you have iWhatever. But for TV you still need an Apple box. Most smart TV supports DLNA internally.
I felt so cheated because my smartTV doesn't support DLNA. It does but not wifi streaming across your own network. Worse, some of the same model does support it, depending on the over 20 digit product number!
I was thinking about a media server or a mountable nettop on the TV. Of course I thought of the Pi too, that turned out to be pretty good at it. The Pi is 6 years in the making. While the Chinese strip off the screen of an Android dual-core phone and put everything in a USB sized stick. The latest one is about US $60. This is a no brainer. It's a ready made DLNA server with all the apps you want for it.
It's an awesome chrometop as oppose to a chromebook. You just need to fire up the chrome browser and you are as good as a chromebook with a huge HD monitor. Particularly if you have so many computers, chrome is the best OS. It doesn't matter which computer you use and your work is always on the cloud Google drive.
Basically it's a desktop with a huge monitor. You can also play Android games with a wireless touchpad keyboard instead of touchscreen. It can also be another phone by pairing it with a good quality headset. The TV doesn't need to be on with all voice commands.
That is the reason I didn't go for cordless with extra handsets. Everybody have cell phones and now at home you don't need to pay anything. You can also turn the system into a private exchange. Each cell phone assigned an internal extension like 200,201 .. 202. You can do intercom too. These are supported by PBXes but I'm not sure about the charge.