There are three ways for Bulk/Mass texting:

1. Using Send Bulk SMS button available on object’s list view. With this button, you can send messages upto 200 records in one go
2. Using Campaign object of Salesforce. We provide Bulk SMS button on Campaign which works for classic as well as Lightning. Since Salesforce allow only Leads and Contact to be added as Campaign Member, with this button you can only send messages to Lead and Contact. You can reach out to 50k records in one go using Bulk Campaign option available with Converse Apps. You can send bulk messages from any objects.