The code *#61# followed by pressing the call button on a mobile phone is used to check the status of call forwarding when your phone is unreachable or busy.
Call Forwarding and *#61
Call forwarding is a feature that allows you to redirect incoming calls to another phone number. The *#61# code is a specific query designed to check the settings related to when your phone is unreachable or busy.
According to Ringblaze, *#61# is a feature in mobile networks that allows you to check the status of call forwarding when your phone is unreachable or busy.
Example
If you dial *#61# on your phone and initiate a call, the network will respond with information about whether call forwarding is active when your phone is unreachable or busy, and, if so, to which number calls are being forwarded. This is a quick way to verify your call forwarding settings without navigating through your phone's settings menus.
