Issue in voice traffic

Hello Basel Sabha,

Thank you for reaching out to the community, check & perform the following:

Step1: current UDP time-out value Under the Advance shell [ssh menu > press 5 for the device management > press 3 for the advance shell) 
type the following command:
#show advanced-firewall

Step2: Then increases the UDP time-out to 150 or 300 seconds, with the following command: 
#set advanced-firewall udp-timeout-stream 300
#set advanced-firewall udp-timeout 300

Step3: turns off the preloaded IPS patterns for SIP
#set ips sip_preproc disable

Step4: check the SIP module status:
#system system_modules show

Step5: if you think the protocol is required, you can load/unload with the following command:
To load: #system system_modules sip load
To unload: #system system_modules sip unload

*Note: The commands are persistent even if the Sophos Firewall is restarted.

> If you are using any custom Port for the SIP other than the traditional 5060 then you may use it with the following command below:
#system system_modules sip load ports <custom_port>

> And lastly ensure you've configured a firewall rule for SIP.
Path: Go to Rules and policies > Firewall rules.
Ensure you select the recipient's network in Destination networks. If you want to call any phone, set the recipient's network to Any.

> Also ensure if there is no UDP flood settings enabled.
Path: Go to Intrusion prevention > DoS & spoof protection.
Under DoS settings, clear the Apply flag checkboxes for UDP flood.
Test the VoIP connection.
If this setting resolves the VoIP issue, lower the UDP flood protection values before applying the flag again.
A single value doesn't work for all environments. Adjust the values until you find those that work best for your VoIP setup.

I think Step 3 is a typo and should be:

set ips sip_preproc disable

I think Step 3 is a typo and should be:

set ips sip_preproc disable

Yup, it was thanks Wayne Folta