We have an OS7030 behind our firewall and it is connected to SIP provider.
Following ports have been opened at the firewall:
5060
35060
30000 - 30100
We can make an outgoing calls through SIP with no problems at all. But when we got an incoming call through SIP we can't hear other side, but they can hear us perfectly.
OS software version is 4.40
Any help will be appreciated.
Thank you in advance.