One way audio call for initial 45 to 60 sec and then it become 2 way audio

[axxo2009]

im having strange problem.
I opened RTP ports in firewall.

but when im in 4G internet or extenally get registered and the try to make calls between registered extension. say LAN registered user to WAN registered user. only one way audio is available for 45 to 50 seconds.

external person can hear us but internal registered person cannot hear them. if they wait for 45 seconds then they can hear each other. i dont know why this is happening..

firewall test is not passed. my router modem firewall is dlink.

may i know why it is so...

 

[eddv123]

That sounds a little like a SIP ALG related issue although please describe whether you are using 4G on a smartphone/App or via a 4G router with hardphone or something like that.

3CX App uses the 3CX tunnel for SIP and media on port 5090 where 4G router would be different so please advise.

Still a firewall issue so you must get the checker working first and the I would run Wireshark and see if you can capture anything, although if this is on the App using tunnel it is harder to capture due to encryption.