There are two ways to try out Viber:

• Viber Business Messages API only: create your account and use your 1,500 complimentary messages to try out Viber. 
• Viber Business Messages + Conversations Inbox: sign up for the free trial here. You can try out the Conversations Inbox for 30 days with Viber, including 1,500 complimentary messages during the trial period. After the trial, you can continue using the Conversations Inbox for EUR 149,- /monthly. Viber messages are charged separately and not included in the Conversations Inbox pricing.