OVPN Server for Remote Access to IP-PBX

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SDC-Consult
OpenVpn Newbie
Posts: 1
Joined: Sat Feb 04, 2023 4:30 pm

OVPN Server for Remote Access to IP-PBX

Post by SDC-Consult » Sun Apr 30, 2023 8:21 am

Dear Community,

i like to use mobile phones to access a Grandstream PBX though a OpenVPN Server which is integrated in a local network. So calls can be made worldwide, secure and as a "local" extension of the PBX.

The scenario is as follows:
- commercial router (FritzBox) IP: 192.168.0.6
- Grandstream UCM6301 IP: IP: 192.168.0.230
- PfSense 2.6 Virtual Maschine as OpenVPN-Server LAN-IP: 192.168.0.150
- Android Phone with OpenVPN for Android & softphone
- Windows 10 Notebook with UMTS/4G-mobile connection and softphone

The goal is to build up a OpenVPN tunnel from the mobile devices and to use the softphones on the android and windows 10 devices.

I know that Grandstream offers an own solution, but i want to an more-or-less "independent" solution.

Many thanks for any hints.

Greetings from Germany

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openvpn_inc
OpenVPN Inc.
Posts: 1333
Joined: Tue Feb 16, 2021 10:41 am

Re: OVPN Server for Remote Access to IP-PBX

Post by openvpn_inc » Tue May 16, 2023 11:09 am

Hello SDC-Consult,

The main problem I see with this is the 192.168.0.0 subnet. It is very likely that this is also in use in networks where the mobile phones are, so you would end up with a subnet collision. You could avoid this by changing this subnet to something more unique like 192.168.77.0/24 or something.

One thing you will want to be careful about is ensuring that access is granted using the routing mechanism instead of NAT. That's because VOIP doesn't do well with NAT in general.

However, you are here providing pfsense as the VPN server solution, and not OpenVPN Access Server. OpenVPN Access Server is the commercial solution that OpenVPN Inc. provides as a VPN server solution based on OpenVPN, and this is the public community support forum for that product. But pfsense is a router platform that includes OpenVPN open source software to offer VPN capabilities. As such, support for OpenVPN on pfsense is supposed to be provided by pfsense itself. So I kindly suggest to head there and see if you can get some help there.

Good luck,
Johan
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Answers provided by OpenVPN Inc. staff members here are provided on a voluntary best-effort basis, and no rights can be claimed on the basis of answers posted in this public forum. If you wish to get official support from OpenVPN Inc. please use the official support ticket system: https://openvpn.net/support

Fadim
OpenVPN User
Posts: 40
Joined: Mon May 15, 2023 12:14 pm

Re: OVPN Server for Remote Access to IP-PBX

Post by Fadim » Thu May 18, 2023 9:05 am

Hey @SDC-Consult,
Nice project you've got going on there! As Johan from OpenVPN mentioned, you might want to change your subnet to avoid any potential collisions. For instance, you could use something like 192.168.77.0/24.
In addition, it's important to ensure that access is granted through routing instead of NAT since VOIP typically doesn't work well with NAT.
However, since you're using pfSense as your VPN server solution rather than OpenVPN Access Server, I'd also recommend reaching out to the pfSense community for specific support. They should be able to provide you with the right guidance for your setup.
Best of luck with your project!
Cheers!

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