Antonin waved one hand vaguely, "That is far out of my area of expertise. I can use two-way muggle radio, and the telephone, or cell phone. But I'm not familiar with anything similar in the wizarding world since the floo network went down in England... unless... "
Antonin paced up and down a few times, thinking and trying to recall. "I believe I remember the Wizarding Wireless Network uses certain crystals to power the transmitter and receiver. I have come across references to the ancient Persians using crystal balls spelled in a certain way for two-way communication. Do you think something like that might be what you are talking about?"