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External Clients / Home Office

PeterK

October 10, 2020 01:56

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Hello everybody,

I would like to integrate external clients / Android phones for an S20 / S50 (home office). However, I am unsure which is the right way to go.

1. Do I have to use the Linkus Client with the Cloud Service?
2. I already have a VPN for my notebooks. Can't I simply use the existing VPN with a smartphone and then use a softphone app on the mobile phone or use the Linkus app without cloud service to connect the phone?
3. Should and can I use the PBX's VPN server to integrate external devices?
   If yes, does it have any advantages over the existing VPN?
4. Here I read that the Linkus server also works without a cloud service. So I should go this way too?
5. The documentation says I have to enter the external IP. But I don't have a static external IP, does DDNS work?

As you can see, many questions and I thank you for your time and your answers.
regards

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2 comments

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  Larry Neblett October 10, 2020 11:17

  1. No, you do not have to use Linkus with the cloud service or at all. The cloud service attempts to provide a level of security that is typically not possible when connecting directly to the PBX unless you have an SBC. 

  2. It is not clear what the VPN on your notebook has to do with the mobile phones, but the bottom line is that if you can establish a VPN connection between the device and the router or PBX, then it is just as secure and usable as the cloud service or SBC without the need for either the cloud or SBC. I have plenty of VPN connections and they work just fine. 

  3. The type of VPN is up to you. I always opt for a VPN server within the router. I do so as I am not limited by the type of VPN I want to use (usually IPsec) and if needed, I can share the resources available on the LAN. While the PBX does support OpenVPN as do many of the physical desk phones, I fall into the camp that believes a phone system should be just that and asking the system to do other functions such as being a VPN server or a router is causing the PBX to spend resources managing and supporting secondary functions that are not related to its primary function of being a phone system. I have observed on more than one occasion where relentless attacks on the PBX effectively caused a DoS and the PBX CPU was maxed out trying to defend itself. 

  4. Yes, Linkus can work directly with the S PBX without the need for the cloud service. However, the issue becomes that in doing it this way you may cause the PBX to be open to attacks which is why the cloud service was developed. The issue is that even if you use a decent router which can filter IPs, there is no telling what IP the remote device might get from whatever the connection is. As a result, trying to filter IPs will be a problem as the device could have a different IP at any point in time, so most will have to open the ports up to all, which of course will be found out by all our friendly hackers which will then start a feeding frenzy. Using the cloud, VPN or a SBC prevents this. Whichever way you go is purely a personal decision based upon your skill set to implement, the security concerns and how much your willing to spend to obtain that which you want and/or the risk your willing to assume. 

  5. You can use a FQDN, but a static is preferable. 

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  PeterK October 15, 2020 22:38

  Ok, Thanks for the detailed answer.