Yep exactly like that.  Maybe you could even transfer them through lan lines like that I dont know. lol

Actually I dont know what I'm thinking.  Not like dialup though.  What if a radio station wanted to give out 10 free bitcions at some point during the day.  You'd have to be waiting with your smartphone up to the speaker to hear the garbled mess they send through.  Once your phone picks up the garbled mess it decodes it and you get your bitcoins. 

Not sure if something like that would work with blockchains and what nots.  Just an thought.

 

If it has to be audible, the max bitrate is about 3~4Kbps IIRC. Or 0.5KB/s, no idea how large is a bitcoin send/receive packet though.

At first i thought this was about performing transactions using audio to transport the transaction request for the first time, for things like a blind client in a mobile that doesn't got a fresh blockchain, only the private key of an address that was expected to have money (so you could for example use a cheap(er) device that doesn't got an internet connection, walk to a vending machine, press a couple buttons and place the device against the mic of the vending machine, and the vending machine would relay the transaction to the internet); i'm not quite sure now....

Thanks for crushing my dreams of winning 10 btcs by holding my phone up to the speaker of my favorite classic rock station bro.

Telephone and AM/FM radio coverage is more complete than BT/Wifi/IR so there could be some situations where being able to transact via audio might be useful. Not a lot but possible.

But can you install custom software in such devices? And are they even powerful enough to decode data from the audio stream without the addition of a dedicated chip?

It's funny, because I have been thinking about this EXACT thing for the past week. I was thinking that there could be a bitcoin transfer protocol which would use an audio signal to send bitcoins to a near by device. Here is what i wrote up over the past week:

While thinking about how to simplify bitcoin, I stumbled upon something. I don't know how unique this is or how well it could work, but here it is.

Cell/Smart phones are some of the most abundant devices around, however, they typically do not support many features due to hardware limitations, bluetooth or wifi are out of the question for the vast majority. However, there are two components that all cellphones have: a microphone and a speaker. What if we could use these to facilitate in person bitcoin transactions?

The following is my attempt at creating a protocol for audio bitcoin transfers. It is not limited to cellphones nor is it limited to an audio signal.

1) Protocol initiation signature + encryption flag
Enabled devices could be continuously listening for an audio signature which would indicate a bitcoin transaction request. And an encryption flag, responding to this flag with an encrypted acknowledgement would allow you to connect ONLY with a trusted party.

2) Bitcoin address  - an appropriate address is sent/requested as a part of the header

3) BTC amount - a number indicating how many bitcoins will be involved in this transaction. Entering a wild character (*) could allow the other party to choose how much they want to send.

4) Name/Message - a limited length name or message to help manage an address book or to say something like 'thank you'


5) Confirm and close transaction.

There could be some sort of volume control to help prevent interference with other devices near by.

Example of use 1
I go shopping in a super market, I pick out my products and then go up to the cash register, the cashier and the cashier scans all my products and hits the request payment button, immediately my device vibrates to alert me of a payment request, I swipe 'O' on my touch screen to accept the request and the transaction is done!

Example of use 2
A charity wishes to collect donations for their cause or maybe a politician wants to raise some funds for their campaign. While doing a presentation, they broadcast their address and all listening devices are alerted of an incoming address, to which they can send any btc amount.

all we need is a small door, and we're in! Sure, it may not be as easy to program an old phone as it is a current gen smartphone, but thats no excuse not to try! http://www.cellphonehacks.com/