Auto-Provision Through VPN?

[Scythe99]

Hi there,

I've been looking through the forums, trying to find a solution to a provisioning problem I've been having. Let me quickly run through my network map:

Building A - 192.168.0.0/24 [3CX Server is here @ 192.168.0.25]
Building B - 10.0.1.0/24
Building C - 10.10.1.0/24

All three of these buildings and networks are currently connected via VPN. I can ping the 3CX Server from each building, no problem. I have Cisco SPA phones at each building, and they all work perfectly and have for years now.

However, I am in the process of upgrading the older phones to newer models. I've used a snom870 and am now playing around with a Grandstream 2170. Both of these use the auto-provision function quite well in my local building [Building A].

In Buildings B and C however, the function does not appear to work. I've read some things about allowing multicast over the VPN, but I'm having some issues getting that working. Am I on the right track, here? If I'm able to get multicast going over the VPN, will the phones show up in the Web GUI and allow me to easily auto-provision them?

Any help would be very greatly appreciated.

Thank you!

 

[FS_Mathieu]

Hello @Scythe99

I heard about using DHCP option 66 previously but never tried it. https://www.3cx.com/sip-phones/dhcp-option-66

 

[diamond9]

You will need to enable multicast routing over your VPN

 

[eddv123]

We use DHCP option 66 all the time with Yealinks and Cisco across VPN connections it works very well: https://www.3cx.com/sip-phones/dhcp-option-66

Just ensure that you have a local DNS resolution record on your local DNS server pointing the 3CX FQDN locally.

In regards to PnP provisioning across the VPN tunnel it is in a different subnet so not initially possible. In theory IPSec over GRE could be possible as GRE supports multicast traffic (which PnP provisioning uses) however I don't know anyone who has done this so would stick with option 66.

Note: Obviously Cisco's are not supported/preferred phones so will not support PnP provisioning, anyway, PnP is only available with supported/preferred models only: https://www.3cx.com/sip-phones/

 

[JohnS_3CX]

Auto provision relies on two things:

• Multicast from the phones must reach the PBX (they will appear under Phones)
• Phones must be able to send and receive traffic from the PBX (to download the provisioning file)

It looks like your issue is the multicast messages and probably also the fact that your phones are in another subnet.

https://www.3cx.com/docs/plug-and-play-ip-phone/