What is that screechy sound produced when a cellphone is placed near a radio?

The loud static heard from the computer's speakers everytime the phone would receive a message or a call is due to electromagnetic interference or EMI. This is what happens when radio waves emitted by one device cause undesirable behavior in another. Thus, placing a cell phone near a computer may create network interference and a screechy sound or noise is often heard from the cell phone when it's trying to transmit or receive a signal.


Sources:

What's the Buzz?Harnessing Static To Improve Wireless Signals.www.sciencecodex.com/whats_the_buzz_harnessing_static_to_improve_wireless_signals

Why does a cell phone produce a screechy sound when placed near a computer or a radio? www.sciam.com/article.cfm?id=experts-cell-phone-screeching