Extend customer journeys using custom channels
Customer journey orchestration in Dynamics 365 Marketing lets marketers create multi-step, multi-channel marketing campaigns that target a specific segment, deliver marketing email messages, respond to contact interactions, launch workflows, and more. More information: Use customer journeys to create automated campaigns
Customer journeys are built by adding tiles from the in-place menu on the designer canvas to build the journey execution flow. Beyond the out-of-the box tiles provided for customer journeys, partners can create custom channels to extend the marketing capabilities in Dynamics 365 Marketing.

You can create a custom channel, such as text (SMS) or social media, and expose the channel as a “tile” in the journey designer and make it accessible from the in-place menu on the canvas under the "Custom tiles" category. These custom channels provide similar capabilities to the out-of-the box channels, including sending communication, tracking customer interactions, and adding if/then conditions to branch the paths within a customer journey.