Voice not being heard when firewall inspects the traffic

Hi, The IVR is clearly heard and the agents answer the calls as well when there is no firewall in the topology. When I place the firewall in the network, PJSIP session gets established. Asterisk plays the IVR but the caller can’t hear any voice. Wireshark output shows that the RTP session is going one way only i.e. from the Asterisk server to the service provider’s server. The Asterisk server disconnects the call automatically after 31 seconds because of no RTP activity. On the firewall NAT and port forwarding are enabled. In the rtp.conf file ports 10,000 to 20,000 are defined and firewall is also allowing RTP ports ranging from 9000-60,000.

The below wireshark output shows the translations being done by the firewall.

pjsip.conf includes the below configuration

[SimpleTrans]
type=transport
protocol=udp
bind=0.0.0.0:5064
local_net=10.0.7.1/29
external_media_address=192.168.90.50
external_signaling_address=192.168.90.50
qualify=yes
nat=force_rport,comedia

Please assist in troubleshooting the problem. thx