Cyber Espionage via Mobile Phone
It is said that NSA whistleblower Edward Snowden would leave his mobile phone in another room during important negotiations. The former employee of a company associated with the U.S. National Security Agency was well aware of the threat posed by phones and how often intelligence agencies use mobile devices for cyber espionage against individuals of interest.
Advice
During important negotiations, your phone should be in another room.
Many people consider the advice given above to be excessive and simply turn off their mobile phones during important negotiations. This is a controversial decision, as malware can modify the phone's operation, and turning it off may not be effective: visually, the phone may appear to be off, but it can continue to record everything around it.