Being able to communicate through thoughts is seen as a super power reserved for aliens or X-men. Actual transmission of thoughts from person to person still appears to be out of reach, but the illusion of telepathy can be implemented with current technology. The technology can be broken into two main steps: Sending and receiving messages.
Receiving messages: I’ll start with the easier of the two technologies since this is already being done commercially through the use of bone conduction. This device conducts sound into the inner ear, bypassing the ear canal so that only the wearer can hear what is being transmitted. The devices currently look like bands that wrap around the head, but they could be miniaturized to small modules that are hidden under a persons hair giving the illusion that no device is there.
Sending messages: This is not as widely used since the technology currently seems to be more difficult to perfect but everyone is aware that Professor Stephen Hawking was able to communicate with people even though he was unable to physically move or able to speak words. From what I understand, he was able to speak through a combination of subtle jaw movements and eye tracking, but perhaps this technology could be improved to the point where only the jaw movements were necessary for a device to understand what words you wanted to say. The other advantage Stephen Hawking had was that he could see what he was writing before he sent the message, so no weird autocorrecting situations. The technology would need to advance to the point where the person could send a message confidently without a display screen to check the accuracy of the message.
With these two technologies, people could talk to each other without any obvious indication that they are communicating, giving the illusion of telepathy. This technology could also be used to individualized advertising. While watching the Minority Report, they have the scene where John is walking around the mall and the ads are making personal statements to everyone. I thought it was a bit awkward and invasion of privacy that these signs are talking to individual people in a public setting, but using the bone conduction “headphones” these ads could address the people individually.
Another outcome of this technology is instant translation of languages. Since the messages are being sent non-verbally, a software could instantly decrypt the message and translate it making it a kind of universal translator