The default channel determines how new contacts are subscribed when they are created. You can choose Email or SMS. This setting is used when contacts are created through forms or surveys, added via integrations, or imported without an explicit channel preference. If a contact explicitly opts into a specific channel, that choice always takes priority.
The default channel affects the initial subscription status for new contacts, which channel is used by default when sending posts and campaigns, and how contacts are included in consent-based segments. You can always refine delivery later by using segments and consent filters.