If you're all worried about security, be assured there is NONE. Assume you're always being listened to.
Business people traveling to China know that they can't bring their personal cell phones with them, because of espionage concerns. ANY cell phone is subject to evesdropping, even if it's OFF. They can even browse the information on your phone if it's off.
From
Covert listening device - Wikipedia, the free encyclopedia) :
"Mobile phone (cell phone) microphones can be activated remotely, without any need for physical access.This "roving bug" feature has been used by law enforcement agencies and intelligence services to listen in on nearby conversations. A United States court ruled in 1988 that a similar technique used by the FBI against reputed former Gulfport, Mississippi cocaine dealers after having obtained a court order was permissible."
From:
https://www.schneier.com/blog/archives/2012/02/computer_securi_2.html
"When Kenneth G. Lieberthal, a China expert at the Brookings Institution, travels to that country, he follows a routine that seems straight from a spy film.
He leaves his cellphone and laptop at home and instead brings "loaner" devices, which he erases before he leaves the United States and wipes clean the minute he returns. In China, he disables Bluetooth and Wi-Fi, never lets his phone out of his sight and, in meetings, not only turns off his phone but also removes the battery, for fear his microphone could be turned on remotely. He connects to the Internet only through an encrypted, password-protected channel, and copies and pastes his password from a USB thumb drive. He never types in a password directly, because, he said, "the Chinese are very good at installing key-logging software on your laptop."