Final answer:
The default channel for a case created through a portal is typically the Web. This is because portals are online platforms where users submit requests via web forms or interfaces.
Step-by-step explanation:
When a case is created through a portal, the default communication channel is typically considered to be Web. Portals are online platforms that enable users to interact and submit support cases or requests through web forms or other web-based interfaces. In the context of customer support systems, cases created directly on the company's support site are generally categorized under the web channel, as this is the medium through which the user has chosen to initiate contact.