Techniques described herein are directed to utilizing an interposing phone number and associated phone tree to direct phone calls intended for a merchant to a customer-facing user interface that facilitates online requests to integrate multiple input channels (e.g., requests made by phone and requests made online) into a single output workflow. An interposing phone number provided by a third-party service can be associated with a merchant profile and an interposing phone tree can be implemented in association with an incoming call directed to the interposing phone number. A path of the interposing phone tree can cause a message including a link to be sent to a mobile device associated with the incoming call. Responsive to receiving an indication of activation of the link, an instruction can be sent to the mobile device causing a customer-facing user interface to be presented to enable a customer to interact with the merchant.