Solved Direct Sip/stun unable to make calls inside the network

[Sprockwell]

we're trying to get our phones configured to allow them to be carried to and from the office, without an SBC.

phones work fine inside the network when provisioned with "Local Lan"

phones work fine when outside the network when provisioned using "direct sip - stun (remote)"

however when i try and provision a phone using direct sip -stun (remote) inside the office the phone appears to provision correctly, but is unable to make or receive calls throwing the message "invite request no response"

the phone is a yealink T29G any help on where to start would be appreciated

 

[AWS2P]

however when i try and provision a phone using direct sip -stun (remote) inside the office the phone appears to provision correctly, but is unable to make or receive calls throwing the message "invite request no response"

Do I understand well ? you try to use STUN on phones connected to same LAN as PBX ?

 

[leejor]

Check the 3CX Activity Log to see what the Invite looks like, and how the set is attempting to register.. I have to assume that it is sending somewhere that doesn't not work from inside your LAN, your FQDN perhaps.

https://www.3cx.com/blog/docs/how-to-create-internal-fqdn/

 

[Sprockwell]

Do I understand well ? you try to use STUN on phones connected to same LAN as PBX ?

i'm trying to provision in a way that would be compatible with either location

 

[leejor]

i'm trying to provision in a way that would be compatible with either location

Then, if you have not done so already, you will want to make your FQDN work from your LAN so that the set can contact the server from in, and outside your network using that one server entry.

https://www.3cx.com/docs/creating-fqdn-split-dns/

 

[Sprockwell]

thank you lee. it seems this may be what we're missing. i will report back once we have a chance to set that up.

i have captured the call attempt in activity log with high verbosity but i'm having trouble reading it.

i will post that here if the split dns instruction doesnt help.

 

[leejor]

You won't need Verbose setting (overkill), to see where the set is sending a registration. It will probably confirm that it is trying the FQDN internally, and cannot resolve correctly.

 

[cobaltit]

Or more likely that it is resolving and is trying to do NAT loopback. Split DNS is the answer

 

[JohnS_3CX]

When the phone tries to connect to the FQDN it resolved the same public IP as the one it's behind.

It then tried to send traffic out and return back in to the PBX (hairpin traffic) and your firewall most likely blocked it.

 

[Sprockwell]

yes split DNS did the trick, thank you everyone.