Slack offers Free Trial, but Callbox does not.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Callbox is designed for Large Enterprises, Small Business and Medium Business.
The starting price of Slack begins at $2.67/Month, while pricing details for Callbox are unavailable.
Some top alternatives to Slack includes Microsoft Teams, Glip, Google Chat, ChatWork, Dialog, Office Chat, imBee, Takle, SPACE Channel and Teamwork Chat.
Some top alternatives to Callbox includes and undefined.