Yes, it's possible to change or remove the login music for an agent's phone login. Access your phone system settings and replace or disable the "do_issabel_dream_of_electric_sheep.wav" file. Refer to available ringtones: Song Ringtones
maybe someone will be interested in a site where you can download ringtones to your smartphone https://ringtoneline.com
You can customize them in settings or check out more ringtones at xiaomi csengőhangok