Two SBCs on same public IP and port- can't provision phones

[kseba77]

I have a segmented our phone network to cut down on the number of phones on each SBC to about 50 (we have a total of 120 phones).
I installed the first SBC and it is working without issue. Now I have installed another on (deferent internal network/switch)/same firewall external IP and I see the phones showing up in 3cx but when I try to assign them nothing happens. The assigned phone shows up in the extension but it is never really provisioned. Also Statistics for that SBC show "Agents Behind SBC: 0".
Do I have to change the port on the 2nd SBC for it to work correctly? What else am I missing?

thanks

 

[JohnS_3CX]

Hi,

Since it's on a different internal network and switch, I would quickly swap the SBCs if I were you and see if the problem follows the SBC or if it stays with the network

 

[kseba77]

I actually just noticed something that might explain the issue.
The working SBC phones IP shows as follows in the PBX:
192.168.11.xxx:5060 via SBC 192.168.11.10:5060

The one with the issue:
192.168.12.xxx:5080 via SBC 192.168.12.10:5060


Is it "normal" that the 2nd one is using port 5080? Also, does it mean I have to open that port on the firewall?

 

[JohnS_3CX]

Yes, that is the port that the specific phone reports when you factory reset it.

Once that phone becomes provisioned and registers, it will show as
192.168.12.xxx:5060 via SBC 192.168.12.10:5060

 

[kseba77]

I see, thank you. Is it also ok for both SBCs to be on the same external port and IP address?
If that is the case I will restart the SBC and monitor my network to see if anything is being blocked.
I can not move the other SBC to test on this network as I have people working on those phones already :-(. Can try it after hours maybe.

 

[JohnS_3CX]

You can have many SBCs behind the same public IP, this should be no problem.

You do not need to port forward anything, so long as your firewall allows outgoing connections

 

[Alphabetic]

Why did you segment the network to split phones between 2 SBCs?

Phones are assigned to SBCs via 3CX.

I can see why you'd move SBCs on different switches. But, why different subnets? Unless you're network is that large anyway.

 

[kseba77]

Why did you segment the network to split phones between 2 SBCs?

Phones are assigned to SBCs via 3CX.

I can see why you'd move SBCs on different switches. But, why different subnets? Unless you're network is that large anyway.

Trying to divide the system in case of failure hence two switches. No real reason for different subnets but since two separate switches with physically separate wiring I figured why not?

 

[kseba77]

Ok, just for everyone's information. The issue was my DHCP providing two DNS servers to the phones. One of them was not suppose to be there :-(. Removed the entry, restarted the phones and everything works as expected. Thank you!

 

[TheRydad]

Why did you segment the network to split phones between 2 SBCs?

Phones are assigned to SBCs via 3CX.

I can see why you'd move SBCs on different switches. But, why different subnets? Unless you're network is that large anyway.

Hijacking this thread a bit because it made me wonder...

Can you have multiple SBCs on the same subnet? Will the phone "attach" to the first one that responds when it is first being provisioned?

-r

 

[Alphabetic]

You can have multiple SBCs on the same network and split phones between them. You'll probably see the phones show up twice in the phones page like Phone1@SBC1 and phone1@SBC2 - from there you can assign the phone to an ext

 

[TheRydad]

You can have multiple SBCs on the same network...

Thanks. That makes sense now. Glad to know about that.

-r

 

[Saqqara]

Hijacking this thread a bit because it made me wonder...

Can you have multiple SBCs on the same subnet? Will the phone "attach" to the first one that responds when it is first being provisioned?

-r

When you assign the phone to an extension, you enter the required sbc server in sbc field