With a DVB/Radio link to the network one could listen to transactions only to their address. You could think of bitcoin operated gas stations, bitcoin network-hubs in rural areas, micropayments to car-charging stations (all you need is power and a cheap DVB receiver to listen to the address "beacon" for a payment.
Now sending back transactions to the network is not covered, but can be done by using SMS or a small radio link to a local node. A bitcoin transaction is only about 64 bytes (!) so even a DTMF call or SMS should work fine.
A transaction send would look like this (normal TXid, in hex)
is just a transaction ID, not a transaction. A full transaction is longer. For example [1], a typical transaction with 1 input and 2 outputs, is 226 bytes.
The idea is that the payment receiver doesn't need to do it. The payee needs to have some kind of uplink (like a mobile phone, amateur radio, or anything).
There are mobile payment applications already, but they are doing it using centralized service and they need make deals with payment agents. With Kryptoradio it is possible to receive payments without any extra middlemen.
Now sending back transactions to the network is not covered, but can be done by using SMS or a small radio link to a local node. A bitcoin transaction is only about 64 bytes (!) so even a DTMF call or SMS should work fine.
A transaction send would look like this (normal TXid, in hex)
That would be in DTMF. Would take about 15 seconds to complete (http://www.audiocheck.net/audiocheck_dtmf.php)