Info for remote connections of phones

[Maggiore81]

Hello
I have 3cx v16 latest, on a debian machine in my office.
The ports are opened on the router, the network is as the following:
OFFICE LAN: 192.168.101.0/24
router .254
3cx .252

the phones in the LAN are in the 192.168.101.0/24 subnet and they works perfectly.
I have two remote ipsec vpn and the connections are coming from 192.168.102.0/24 and 192.168.100.0/24 coming to the 3cx internal IP 192.168.101.252 and they works perfectly.
I use also 3cx apps on some mobile phones, they connects to the public hostname (with forwarded ports) pbx.mycompany.com and they works.
We use yealink phones in the office.

I have now some questions that I cannot resolve:

a) What if I have a remote office and without any VPN, I would like to provision the phone and connect it to the public ip pbx.mycompany.com.

I tried to change the provisioning interface on the pbx but it doesnt work.

I would like to have one phone (for example yealink T21P) at home to connect to the public ip of the pbx, but I am not able to do it. Can someone help me?

 

[diamond9]

you need to change the provisioning method of the extension to STUN this will then give you the link to put into the provisioning element of the phone

https://www.3cx.com/sip-phones/yealink-t20p-t22p-t26p-t28p/
you need to follow the remote phones section of the instructions.

Regards

 

[diamond9]

Also, just reading the limitations, you will need to disable SSL/SecureSIP Transport and Ciphers
under advanced and security

 

[Alphabetic]

Also, 3CX's SBC on a Rasperry Pi would be a good solution for you remote offices with no VPN capability. Management is a lot easier and you dont have to mess around opening ports and stuff. Pi's are very cheap and easy to deploy.

 

[Saqqara]

If you have move than one phone at each remote office, look into SBC else you will have to do the following for each phone.

1. Give it a different SIP port
2. Give it a totally separate RTP Ports.
3. Give the phone fixed IP address (can be done via DHCP)
4. Setup port forwarding rules, so that the required sip , rtp ports are directed to the correct phone

https://www.3cx.com/3cxacademy/videos/intermediate/configuring-remote-extensions/

 

[diamond9]

I dont understand why you need to do any port forwarding at the remote site, i have sites with multiple STUN provisioned phones and there is no need to forward ports

 

[Maggiore81]

Hello I tried but with no avail. I am not able to connect the remote phone. I have seen the connection going out from the phone to the remote PBX, on remote port 5001. But No provisioning, no entries in the 3cx logs. nothing.

 

[Alphabetic]

Check you're on the latest supported firmware for your phone. https://www.3cx.com/support/phone-firmwares/

Check that you have not disabled access for remote working under the extension settings. its called something like "Disallow use outside of network"

 

[Saqqara]

Have you open up port 5001 on the firewall, as this is required to provision the phone.

Have you unticked 'Disallow use of extension outside the LAN (Remote extensions using Direct SIP or STUN will be blocked)' under options

Have you disabled 'Only Accept Trusted Certificates' on the phone via the phone gui - settings is under Securitty - Trusted Certificates. - https://www.3cx.com/sip-phones/yealink-t20p-t22p-t26p-t28p/
known limitations section

Check 3CX blacklist , and remove any IP's

Have you configured the correct mac address within 3CX management console.

If all the above is correct, factory default the phone and it should get logon prompt on the screen

 

[Maggiore81]

Hello. I have opened the port, the connection goes to established.
I have unticket the "disallow ouse of extension..."
I have enable PBX delivers audio
No ip in blacklist
Correct Mac address set.
I will try again

 

[SteveITS]

3CX's SBC on a Rasperry Pi would be a good solution

Would installing the SBC software on a Windows PC at the home work? Would it work if the phone was between the PC and the wall (PC->phone->Ethernet)? Obviously the phone would then only work if the PC was on.

 

[Maggiore81]

I tried. then works, the phone registered succesfully. Now I cannot make calls, I dont hear audio.
I have checked the ports and are all opened as by guide. Remote 3cx apps works. I pass perfectly the firewall checker of 3cx. All ports are correctly opened. I have logged the connections from the remote phone, it uses the local port 14000-14014 that I opened to it... but no avail.

 

[Saqqara]

What happens if you do the echo test *777

Have you ticked “PBX Delivers Audio” for the extension

 

[Maggiore81]

Hello. Nothing works.
I cannot hear anything.
If I disable the PBX delivers audio, I cannot hear anything (i am in office with a working 3cx phone) but the guy on the remote extensions can hear me.

 

[JohnS_3CX]

For a STUN phone audio transport to work:

1) PBX must pass firewall checker on audio ports
2) The remote phone must have its audio ports forwarded on the remote firewall
3) PBX Delivers Audio must be on

Kindly doublecheck these 3 points