When a physical phone is provisioned and registered in a Genesys Cloud organization, certain configuration details, such as the Line Appearance ID, are stored in Genesys Cloud and on the phone itself. If you later remove/replace the physical phone and do not intend to reuse it in your Genesys Cloud organization, you should perform a factory reset on the phone. Doing so will prevent potential Line Appearance ID conflicts should the phone ever be inadvertently reconnected.