I have seen lots on the net about one way audio and mostly always points to the firewall but I just can't see what I have done wrong.
I will try to explain what has been done.
We have a mitel 3300, our network is small so we only have the one van, let's say 192.168.10.0/24.
Our mitel switch is 192.168.10.60, with a gateway of 192.168.10.1, dhcp is being via a server so switched off on the mitel, the want port is also disabled and the subnet is in the ip network parameters.
We have a fortinet 60d firewall.
I have created inbound and outbound rules.
Internal to wan - source = mitel switch, destination = any, NAT = enabled using outgoing port ( let's say 234.123.123.10)
Wan to internal - source = any, destination = mitel vip, NAT = mitel_ippool
The mitel vip is a straight one to one static nat 234.123.123.11 to 192.168.10.60
The mitel Ippool is an external range containing just 234.123.123.11
Sip helper has been deleted and sip alg in the voip profile disabled.
When I call a mobile from a mitel phone they can hear me but I can't hear them.
Hopefully someone can point me in the right direction.
(Ip addresses are fictitious)