Comment by Coeur
"Mobile phone (cell phone) microphones can be activated remotely, without any need for physical access"
https://en.wikipedia.org/wiki/Covert_listening_device#Remote...
And the linked sources are:
- Kröger, Jacob Leon; Raschke, Philip (2019). "Is My Phone Listening in? On the Feasibility and Detectability of Mobile Eavesdropping". Data and Applications Security and Privacy XXXIII. Lecture Notes in Computer Science. Vol. 11559. pp. 102–120. doi:10.1007/978-3-030-22479-0_6. ISBN 978-3-030-22478-3. ISSN 0302-9743.
- Schneier, Bruce (5 December 2006). "Remotely Eavesdropping on Cell Phone Microphones". Schneier On Security. Archived from the original on 12 January 2014. Retrieved 13 December 2009.
- McCullagh, Declan; Anne Broache (1 December 2006). "FBI taps cell phone mic as eavesdropping tool". CNet News. Archived from the original on 10 November 2013. Retrieved 14 March 2009.
- Odell, Mark (1 August 2005). "Use of mobile helped police keep tabs on suspect". Financial Times. Retrieved 14 March 2009.
- "Telephones". Western Regional Security Office (NOAA official site). 2001. Archived from the original on 6 November 2013. Retrieved 22 March 2009.
- "Can You Hear Me Now?". ABC News: The Blotter. Archived from the original on 25 August 2011. Retrieved 13 December 2009.
- Lewis Page (26 June 2007). "Cell hack geek stalks pretty blonde shocker". The Register. Archived from the original on 3 November 2013. Retrieved 1 May 2010.
So specific models from before secure operating systems like Android and iOS. Now those operating systems even show an indicator whenever they are recording.