The Avaya Equinox Client requires the 46xxsettings.txt file in an Avaya IP Office deployment to read the SIP values from the file in order to connect to the Avaya IP Office system. These SIP values can include the IP address of the Avaya IP Office system, the SIP port number, and the SIP user name. The Client does not use conference settings contained in the file to connect, nor does it write any SIP values into the file or log connections in the file.
Reference:
Avaya IP Office (https://www.avaya.com/en/solutions/ip-office/).
Avaya IP Office Equinox Client (https://www.avaya.com/en/solutions/ip-office/equinox-client/).