There are only two types of firmware for the IP Phone 7800/8800 series: Enterprise and MPP. The 8875 and 9800 series run PhoneOS which, for now, mostly just dual boots the device between Enterprise and MPP depending on the call control platform. SIP is the call control protocol in all scenarios though. Enterprise is only intended for Cisco on-premises call control products CUCM or CME and Webex Calling Dedicated Instance (WxC-DI); MPP is intended for everything else, including Webex Calling multi-tenant (WxC-MT).
Custom ringtones are linked from the phone admin guide to the CUCM feature guide. I couldn’t find a search result that covered admin control of noise removal and don’t have a CUCM cluster in my lab anymore to check. If the toggle exists, it would be in the Model Specific Configuration Parameters section of the Device Config page.
