To set up SMS logging in salesforce, the following steps need to be followed:
1. Navigate to the Setup Page:
2. Navigate to Object Manager:
3. Find an open task object:
4. Open Fields and Relationships and Open ‘Type’:
After opening the Task object scroll down to Task Type Picklist Values. Click on New and add type SMS
5. Open ‘Set field level Security’ and mark Visible for all.
Now your SMS activities will be logged in Salesforce.