We are considering Zoiper 5 pro for our call center.
We have 15 agents currently.
Do we need to purchase 15 license or 1 license to handle our operation?
How many installation does it support per license?
I suggest that you contact the Zoiper sales team through the contact form, here: https://www.zoiper.com/en/contact
The licensing policy is per-device/ per OS/ per seat. This means that you can use one Zoiper license for one computer for one user at a time(all user accounts on the computer will have access to Zoiper Pro). You cannot place one license on a terminal server and make multiple session simultaneously.
I think you only need one license, but after you have taken and you are not able to use it, then i will suggest you to contact sales team.
the sales team should help. I too was once a time when you had to address to them and they here are absolutely competent helped me