Explanation
Box 1: Workstream
Configure work distribution
In the Work distribution area of a workstream, you can either accept the default settings or select See more and update the following options:
Auto-close after inactivity
Work distribution mode
Capacity
Block capacity for wrap up
Etc.
Box 2: SMS Number
In SMS phone numbers, select Add, and enter the following details in Add SMS number:
Number: Specify the support phone number that you purchased from TeleSign in the <phone_number> format, such as 14252306549. Make sure that you don't enter blank spaces or special characters.
Type: Select Geo, Short code, or Toll free.
Description: Enter a description.
Validate: Select to validate the customer ID and API key.
Reference:
https://docs.microsoft.com/en-us/dynamics365/customer-service/configure-sms-channel