The Bulk Text (List View) button feature can be configured for all objects like Contact, Account, or any other custom object.
ValueText App Exchange package installation will enable you to have a “Send SMS” or “Bulk SMS” button for contacts, accounts, cases, leads & opportunity objects.
How to create a “Bulk Text (List View)” button for Custom Object:
Log in to Salesforce > Setup > Create > Objects > Select object which you want to create a button for > add “Buttons, Links and Actions” sections > click on “New Button or Link”.
Click on “List Button” > Behavior: “Display in a new window.” > Content Source: “URL”.
Copy and paste the below code in the formula window:
Replace “ObjectAPI-Name” with a custom object API name. For Example: for a contact object, “Contact” and click on the Save button.
Once saved, you need to add the button from “search layout for salesforce classic” for user access.