Digital Engagement Messaging allows customers to start conversations by sending texts to your designated phone number or sending Facebook Messenger messages to your Facebook page. Incoming messages are displayed in the Omni-Channel utility in the Service Console, where agents can accept a message and start chatting with a visitor.

Conversations can be initiated directly with customers within Salesforce through outbound message notifications in Process Builder. When a customer wants to respond, their incoming responses are routed directly to the Service Console where agents can continue the conversation.

LOA form is used if the customer wants use their number instead of Salesforce generated number.

Area code can be shared to Salesforce to get a number starting with the Area code.

To know more about Carrier Filtering and Best Practices, please check the below link
https://help.salesforce.com/articleView?id=000352415&language=en_US&type=1&mode=1

 

Chat using Queue-Based Routing – https://www.infallibletechie.com/2021/01/queue-based-chat-routing-in-salesforce.html
Chat using Skill-Based Routing – https://www.infallibletechie.com/2020/06/route-chats-via-skills-based-routing.html
Route WhatsApp Messages using Queue-Based Routing – https://www.infallibletechie.com/2021/03/how-to-route-whatsapp-messages-to.html
Handle incoming SMS Messages without an Agent in Salesforce – https://www.infallibletechie.com/2021/03/how-to-handle-incoming-sms-messages.html
Bulk Message – https://www.infallibletechie.com/2021/01/how-to-send-mass-or-bulk-sms-messages.html
SMS Channel Setup – https://www.infallibletechie.com/2020/04/sms-channel-setup-in-digital-engagement.html 
Facebook Channel Setup – https://www.infallibletechie.com/2020/04/facebook-channel-setup-in-digital.html