If the server operate from a LAN IP or behind a router/firewall, then the router/firewall must have all of the ports listed below opened/forwarded.
Web GUI:
TCP: 80, 81, 443
.
SSH access:
.
PBXware
TCP: 2020
.
SERVERware
TCP: 2020, 2222
.
SIP traffic:
TCP: 10001, 5060-5069
UDP: 4000-4999, 5060-5069, 10000-20000
.
IAX traffic:
TCP: 5038, 5037
UDP: 4569
.
PWProxy
v5.x
TCP: 10005
v6.x
TCP: 10005, 10007, 10009
.
Jabber traffic (deprecated from v6.0):
TCP: 5222 and 5223
.
Auto Provisioning
TFTP
UDP: 69
.
Central Phone Book (introduced in v6.0):
TCP: 11389, 11636
.
BSSUP
TCP: 2244