Yes, you can. To get you started, we have set you up with $3 of phone credits that you can use to purchase numbers and make calls. If you would like to make more calls, or buy a number that costs more than $3 during your trial, you can purchase phone credits and do so. You do not need to purchase a plan to buy phone numbers or make calls. You have full flexibility to test out different calls and workflows during your trial. The only restriction is that your calls would be limited to 2 mins each.