3cx Call drop sometime how I know the reason

[Jakkapan]

Dear all
I have a problem about 3cx on window.
my client complain about call disconnect how I know the reason

my network have client > Fortigate FW > internet provider (I did fix to 3cx access only 1 link) > 3cx server on provider

SIP trunk not enable on provider
I did disable sip nat on FW and open all port about 3cx on FW.
policy on FW permit any any 1 WAN link

thank you

 

[NickD_3CX]

Hi! Which calls disconnect? Does it happen also when Extension A calls Extension B? Or does it only happen when an Extension calls an External Number?