Does the connection with the virtual PBX require an open port in our firewall?

95% of the time: no. Because of the characteristics of outgoing communications, there is no need to open firewall ports or make any changes in your network. The only exception is a firewall setup with extraordinarily strict outbound rules.

The list of open ports in the firewall necessary For communication with the virtual PBX:

Direction Protocol
Port
Appointment
Outgoing
TCP
80
Web control panel virtual PBX
Both
UDP
5060
SIP alarm system for remote IP phones
Both
UDP
10000-20000
RTP for remote IP phones Astra
Both
UDP
10000-20000
RTP for remote IP phones Polycom
Both
UDP
9710-20000
RTP for remote Soft phones