Steps necessary for multiple remote extensions?

[cgallery]

Both my work and my home networks use dynamic IP's assigned by the ISP.

I use DD-WRT routers at both locations.

Both locations also use dyndns names so I can find them from anywhere.

3CX test server is at work.

I took a single Cisco SPA5108 phone home and configured it per the instructions on the 3CX pages. I only configured the phone, no changes to the router or anything. It worked great.

I then tried adding a 2nd SPA5108 as a new extension at home. Then I seemed to have problems with both remote (home) phones. I couldn't call one phone from the other, for example (I wrote the message from the phone down but it is at home).

The question is, am I supposed to be able to run multiple remote extensions without making any changes to the router? Provided one extension works at a time, should they both work?

It is entirely possible I was having some other form of network problem, so I'm planning on trying this again tonight. Just thought I'd ask if I skipped a step or something before I spend too much time chasing my tail.

Thanks in advance.

 

[leejor]

If you are going to run two SIP devices remotely behind the same router, first of all, be sure that each one has a unique port number. You can leave one at the default of 5060, but change the second one to 5061 or another number. You should not have to set up port forwarding but some routers do have issues sending the voice packets to the correct set. It can be caused by which set placed that last call and which set receives the next call, some times that can confuse the router as it remembers the last IP using that particular voice ports (not the 5060 series port).

You can try changing (playing with) the per line setting in 3CX that force all audio though 3CX. The exact phrasing has changed in Ver 9 but you will see it in there. If you turn that off (or make sure it is off), then a call (voice portion) from one extension to the other, at the remote location, should not travel all the way back to 3CX.

 

[jeffj]

I don't want to give you wrong info - but it is my understanding you need to have stun turned on and run 3CX sip proxy manager (unless it is just for remote PBX connection) on a PC for remote extensions to work. Here is some info: http://www.3cx.com/blog/releases/sip-proxy-manager/ . When you say it was working with 1 phone did you verify 2way audio on that first phone? What I am doing for 3 different locations is running VPN tunnel from each location and all phones at the remote locations can work with those in the office. The office has a static IP though still use dyndns and the remote locations work just fine for they think their on the same network. I did put each remote on a different subnet though.

 

[cgallery]

When you say it was working with 1 phone did you verify 2way audio on that first phone?

I've been making/taking calls on it for a few days, has worked pretty well.

 

[cgallery]

If you are going to run two SIP devices remotely behind the same router, first of all, be sure that each one has a unique port number. You can leave one at the default of 5060, but change the second one to 5061 or another number.

So basically I set the 2nd phone to 5061 and then port forward 5061 to 5060 on the router that my 3CX server is connected to? I'll give it a shot.

 

[Ricambi America]

No. At your remote location, simply assign one phone to be port 5060 (in the phone's control interface.. nothing to do with 3CX directly), and assign the other phone to be 5061.

We use this setup and it works fine.

 

[leejor]

I don't want to give you wrong info - but it is my understanding you need to have stun turned on and run 3CX sip proxy manager (unless it is just for remote PBX connection) on a PC for remote extensions to work.

Yes, you will require STUN to be enabled at the remote sets if they are behind a router. The 3Cx Proxy server, while a useful add-on, if you are running multiple sets at a remote location, isn't really necessary if you just want to run one or two. The proxy server does however allow you to use the tunnel option, which can overcome a number of issues.

 

[cgallery]

No. At your remote location, simply assign one phone to be port 5060 (in the phone's control interface.. nothing to do with 3CX directly), and assign the other phone to be 5061.

We use this setup and it works fine.

I'll give it a shot but I'd have thought the server would only accept incoming connections on 5060, and that if I set the phone for 5061 that it would attempt to talk to the server on 5061? Or does it know enough to talk to the server on 5060 but let the server know it is on 5061?

 

[leejor]

You don't change the port 5060 that you communicate to 3CX on. You change the port number of the device itself. Then 3CX will communicate back to the second device on your remote network at a port other than 5060 that it uses to communicates with the first device.

When a device registers from behind a router at a remote location, it tells 3CX "you can reach me at this public IP AND this port" ,( Public IP + 5060), that would be first device. The second would have to register with something like (Public IP + 5061).

3CX would be confused , and messages would never get to the second device, if both devices registered with the same port number as the public IP will be that same from all devices behind the same router.

 

[cgallery]

You don't change the port 5060 that you communicate to 3CX on. You change the port number of the device itself. Then 3CX will communicate back to the second device on your remote network at a port other than 5060 that it uses to communicates with the first device.

When a device registers from behind a router at a remote location, it tells 3CX "you can reach me at this public IP AND this port" ,( Public IP + 5060), that would be first device. The second would have to register with something like (Public IP + 5061).

3CX would be confused , and messages would never get to the second device, if both devices registered with the same port number as the public IP will be that same from all devices behind the same router.

Ohhhh!!!

My confusion came in wondering how the phone (using 5061) would find the server (using 5060). But I see that one of the phones I have (an Astra 9133i) has the ability to set a "local SIP port." So I tell the phone the server is on 5060, and I tell the phone to use 5061, right?

I'll try it this weekend.

 

[cgallery]

Just a follow-up...

I changed phone #2 to 5061. The phones I'm using are the SPA508G. To change the phone to 5061 I only had to change one field in the phone's setup. That was on the "Ext 1" tab, the "SIP Settings" section, I changed "SIP Port" from 5060 to 5061.

However, that wasn't enough. I also had to add two port forwarding rules to the router. 5060 is set to go to the original (1st) phone, and 5061 set to the 2nd phone.

Until I did that I still had the same weirdness where I'd press a button and it would seem stuck (you'd here the tone for 3x or 4x longer than normal). And calls wouldn't go through. And other strangeness.

Once I did the port forwarding, the problem was solved.

Kinda surprised in a way, as I thought the STUN server stuff would have taken care of this. I had thought that the fact that one phone could work behind the NAT router via STUN would mean that a 2nd phone could do the same. That, the phone knowing it was on 5062 would tell the STUN server it was on 5062 and it stays connected always, so I'd just have thought that would be enough.

 

[Ricambi America]

FWIW, if you can run the SIP Proxy in your remote location, your configuration will be far enjoyable. The SIP Proxy downloads and configurations are in the 3CX WIKI, I think.

 

[cgallery]

FWIW, if you can run the SIP Proxy in your remote location, your configuration will be far enjoyable. The SIP Proxy downloads and configurations are in the 3CX WIKI, I think.

That requires a separate CPU, though, right? I wanted to try to accomplish this with just a couple of phones, no extra CPU's.

 

[leejor]

However, that wasn't enough. I also had to add two port forwarding rules to the router. 5060 is set to go to the original (1st) phone, and 5061 set to the 2nd phone.

On most routers (at the remote location) you can, but shouldn't have to do any port forwarding. When the device communicates outbound, it tells the router where to send inbound messages.

Kinda surprised in a way, as I thought the STUN server stuff would have taken care of this. I had thought that the fact that one phone could work behind the NAT router via STUN would mean that a 2nd phone could do the same. That, the phone knowing it was on 5062 would tell the STUN server it was on 5062 and it stays connected always, so I'd just have thought that would be enough.

STUN is simply a tool that the device (when behind a router) can use to determine its "place" on the net and then relay that information on to the SIP server it is going to register with. In (very) simple terms, it's like calling a friend who has caller ID and getting them to tell you what number you are calling from.

As far as ports go, think of your public IP address as the country/city/and street address of a large apartment building and the port number like the apartment number. You need all of the information (public IP + port number) to get messages to the correct location. In most cases the router (mailman?) will remember where things go, but just to be sure, you can use port forwarding for the ports that don't vary.

 

[joshhough]

Hi there,

I'm having problems trying to connect my grandstream phone to my remote PBX. I want as discussed here 2 or more phones at my office with my PBX on a remote server. I have it working fine on port 5060 with no forwarding rules on my iPhone. However:
1) I can't get my grandstream to connect to my remote PBX at all whereas my iPhone does?
2) If I change the local sip port on my iPhone to 5061, it no longer connects. How can I get around this?

Thanks,

Josh

 

[davidbenwell]

Josh, you should refram from posting the same question in more then 1 thread, it makes the forums messey.

Proxy or Public IPs are what you need.

 

[joshhough]

Sorry my bad - I have the grandstream working now... However my question is now more aimed at the different local ports discussed in this thread.

Does it actually work by doing that? Or will I need port forwarding. Ideally as someone else mentioned I dont really want to run a proxy server as it means I have to have it on all the time. All my internal phones have static ip's so if I simply forward the internal port to each phone would that work?

Sorry if I should be posting this inmyoriginal thread however it appears more relevant to this one.

Thanks,

Josh

 

[leejor]

If you are going to run multiple devices behind a remote router, then each device will have to have it's own port number, 5060, 5061, 5062, and so on. They will all connect back to 3CX on port 5060, unless you have changed the port number at the 3CX end. You should not have to use port forwarding at the remote end, but, I have seen "no audio issues" because the router becomes "confused" about where to send the voice packets. Because these change all the time, you can't forward them. As to whether it all works for you may depend on the number of extensions at the site and the make/model of the router. It won't hurt to try it out, but you may end up having to use the proxy server if you run into audio issues.

As for your iPhone no longer registering, are you sure you changed the correct port? Do you see an attempt in the 3CX logs?

 

[joshhough]

Hi there,

I've got it working and decided to use the proxy for ease. However, i'm getting problems with no inbound audio?

I also have the problem which i had before using the proxy in that none of the phones ring. when checking the logs it says that there is a timeout, however i can dial out absolutley fine, albeit i now have no incoming audio.

[EDIT] - i've looked at the logs this morning and found this: 21:55:58.615 [CM503003]: Call(9): Call to sip:125@[Remote Server IP]:5060 has failed; Cause: 408 Request Timeout; internal - Does that mean that it's not registering the IP address of the external extension using the proxy?

Thanks,

Josh