Agent Desktop connectivity depends on the Webex service domains and the Contact Center service domain being reachable over HTTPS. Cisco's security and network documentation for Webex Contact Center includes domain allow-listing so the browser desktop can load scripts, APIs, authentication paths, media-related services, and Contact Center application components. The official domain patterns include Webex domains such as *.wbx.com on port 443 and Contact Center service domains such as *.ciscoccservice.com on port 443.
Blocking either can prevent the desktop from loading, authenticating, or communicating with Contact Center services. The ucce.com domain is associated with Unified Contact Center Enterprise naming, not Webex Contact Center Agent Desktop. The generic amazonaws.com domain may appear in some cloud service paths, but it is not one of the two direct required domain answers here. The wxcc.com option is also not the official service domain in the documented network requirement list. Reference: Cisco Help, Set up security for Webex Contact Center; System requirements for Webex Contact Center Desktop.