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3CX Skype Connect SIP Trunk Not Working

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buschconsulting

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Hi All,

We have a 3CX PBX System and a Skype Connect SIP Trunk Line we are using. The issue is that Skype calls from the Skype application on a smart phone works every time calling into the PBX. Calling from a computer using the Skype application will just stay there without ringing or connecting.

There were a few times I tested connecting from a computer which was wirelessly connected to the smartphone hotspot that Skype call did connect on the initial call, but all calls thereafter will behave the same without connecting and just hangs.

I have no leads on what I can do at this point and would appreciate all suggestions and assistance.

Thank you.
 
So, if i get this straight, you are using two devices (running the Skype application), to place Skype calls into the PBX, with mixed results.

Are you able to place Skype calls out, from the PBX, over the Skype trunk, perhaps to these devices?

Have you had any other users attempt to call your PBX using Skype?

Is your Skype SIP trunks assigned a "real" telephone number, reachable from any telephone, or is it only a Skype "user name"?

Does the 3CX log show any indication of errors, associated with the Skype trunk?

Did this issue just start, or has it not functioned correctly from day one?
 
Thanks for the prompt response. I am just testing various devices to see what is working with Skype as there are other users who are affected. At this point, only the skype application on our Android phones are consistently connecting to 3CX and all other attempts from pcs/laptops from various users have failed. To answer your questions:

Are you able to place Skype calls out, from the PBX, over the Skype trunk, perhaps to these devices?
- Yes, skype calls outgoing are no problem, I have consistently been able to call out with no issues by forcing calls to only go out skype trunk and watching the status in the ports to ensure they are going through skype.

Have you had any other users attempt to call your PBX using Skype?
- Yes, 3 other users are having same results, works on their Android smartphones, but never from pc/laptop. Even after connecting a laptop to the smartphones hotspot tethering, it does not connect, but from the smartphone skype, works every time.

Is your Skype SIP trunks assigned a "real" telephone number, reachable from any telephone, or is it only a Skype "user name"?
- Yes, there is a real telephone number

Does the 3CX log show any indication of errors, associated with the Skype trunk?
- No indications of issues with Skype trunk.

Did this issue just start, or has it not functioned correctly from day one?
- Since we use this as a backup line, it was working before as far as I know, we were on version 10 at the time and it was on a physical server, since then, I have upgraded this to version 11 and on a virtual server. Somewhere in between these changes it stopped working, but I cannot say the changes caused the issue.
 
So, as I understand it, it boils down to PC users running Skype are not able to call your Skype trunk, but Android devices, and other callers are. So it doesn't appear to be a Skype network issue, as you are receiving some calls, just not those from the PC's you are trying. You are also able to place calls from 3Cx over the Skype trunk.

Are the PC users able to call other Skype users? Are they dialling your "Real" PSTN number (requiring a credit) assigned to your Skype trunk, or a Skype name? As I understand it, there are some restrictions to do with Skype SIP users with "real" numbers and Skype names, inter-calling.

I use a Skype name, in conjunction with the 3CX Skype gateway, in a very limited manner
 
Hi leejor,

Thanks for the quick reply again. Yes, the issue seems to be only occurring on pc/laptop users. From the last 3 Android users with the skype client installed, there were no issues calling into the system. Also, all the pcs/laptops have their firewalls disabled just to ensure it wasn't a port related issue.

I apologize, let me clarify the calling method from the users. From both the Android and the pcs/laptops, users basically log in to their skype accounts and we have a username that they just click on and call. From there, skype connect makes the routing to the skype trunk on 3CX and call connects. I have tested calling to other users with their skype name as well, as we use skype for a lot of communication and I can connect to them skype to skype and pc to pc or android. It's just that when calling this one username connected to our 3cx skype trunk, the issue occurs.

So quick answer to the question if they are dialing to a real PSTN number is no, they are dialing into a name.
 
Then I would suspect something on the PC's. If other Skype users, including the Android devices are able to reach you by using your Skype name, the same one that the PC's are using, then it indicates that Skype is able to route calls to you, and that 3CX is accepting the calls. Unless there is some sort of caller Id/user name blocking happening in Skype, then you may want to try deleting, then re-installing the Skype application on one of the PC's to see if that makes a difference.

Would there not be some sort of error message, at the senders PC, if Skype is having an issue "delivering" the call?
 
Yeah, that's the thing. There is no error message in the skype call. You will see the call, there is no ringing and I leave it for 5 minutes or longer and there is no message aside from one where there is no answer after hanging up. At this point, I think it would be a routing issue and possibly firewall blocking, so I turn off the windows firewall and made sure no other firewalls are installed, but same thing. I was thinking of reinstalling the skype myself and will need to test this.
 
I reinstalled skype and believe that did the trick, thanks. The only other issue now also after testing is that there is a very long lag when I connect to 3CX via SIP Trunk. It takes almost a minute to connect this way and would think most callers would attempt to hang up before they realize it works. Do you know if there's anything that can be done to improve the connect time? Thanks.
 
So is it only the PC's having this delay problem too?

You can see, in the 3CX log the exact second that it receives notification of an incoming call. When it does, I'm going to assume, all programming within 3CX being correct, you are getting calls after all, it will send the call to it's proper destination.

So, if, after receiving a call, there is no delay within 3CX, that leave two places that it could be occurring.

Within the PC placing the call.

or

Within the Skype network.

Is there any delay when you dial you Skype "real" number from a landline?
 
Yes, only the PC's are having this issue. When I make a call from the skype client on the smartphones, no lag. Thinking it's the cell network of the phone, I make the phone network a hotspot and connect a laptop to the hotspot and the lag is there too.

I actually tested, seems like 3CX is not receiving the PC skype calls. I took wireshark logs and I see these about every 30 seconds to a minute that skype is re-registering each time, not sure if this is normal:

SIP 863 Request: REGISTER sip:sip.skype.com:5060
SIP 525 Status: 200 OK (1 bindings)

Here is the wireshark log for the working skype from the smartphone:

SIP/SDP 893 Request: INVITE sip:[email protected]:5060;rinstance=b206b2c37665b71c;transport=udp, with session description
SIP 386 Status: 100 Trying
SIP/SDP 864 Status: 200 OK, with session description
SIP 543 Request: ACK sip:[email protected]:5060;rinstance=b206b2c37665b71c;transport=udp
SIP 864 Request: REGISTER sip:sip.skype.com:5060
SIP 526 Status: 200 OK (1 bindings)
SIP 483 Request: BYE sip:[email protected]:5060;rinstance=b206b2c37665b71c;transport=udp

I am a bit lost, not sure why this is occuring. If it is the skype network, then the why would it work for the smartphone and not the PC?

Finally, for the skype landline, there is no delay. Thanks.
 
Are the PC's having the issue, the same make/model? Could they both running a program (security, firewall?), or share a setting, that might be causing this?

Have you tried installing Skype, on another, unrelated PC, or asking a friend, that has Skype installed, if they could try calling?

As far as the registration time, that is usually determined by the SIP server, in this case Skype. In some cases that can be changed to a shorter value, but anything longer risks loosing registration.
 
Yeah the PCs are not related and different models. They all have different configurations and different apps. I have turned off firewall on the Pcs and still didn't work.

I also have my own personal computers actually which I had tested calling, but also failed. At this point, I don't know what else is happening. This could be a Skype network issue. I might need to contact Skype on this and find out why this might not be working.
 
Have you gone over the 3CX logs, for a call via Skype, from a PC and from an Android phone,or even from a PSTN phone dialling your "real" number, perhaps using the verbose log setting in 3CX.

If they look identical, other than the originators number, including the time from call initialization to set ringing, then I would attempt to illicit help from Skype in sorting this out.

Do they have a help forum that might be of use? I can't believe that you are the first to experience this if it can be re-produced on multiple PC's.
 
I was able to connect with Skype support and finally found the answer. The issue with the Skype client is with all versions currently 6.1 and above. I found a site called http://www.oldversion.com/windows/skype and downloaded the latest 5.10 version there. Once installed, I was able to connect in an instant. So the skype person indicated that they are trying to correct this, but nothing is clear at this point when it will be fixed. Thanks again for all your help, I appreciate it.
 
Sorry about the late entry - But I've been trying to get to the bottom of the slow connect issue myself ...
I see a Skype client time-out after about 60 seconds when I call the Skype ID associated with my Skype Connect trunk - then show itself as 'transferring the call' - which at that point it then starts ringing on my 3CX. Since the Skype ID is exclusively bonded to the Skype Connect trunk, I have no idea what it's ringing for that first minute, before it gives up and transfers???
I've installed a Skype client on my Android phone however, and that gets a call thru' to the 3CX via Skype Connect pretty much immediately ...
I got the same drivel from Skype support i.e. "it has been reported and we're working on it!" - but from the number of like complaints on the internet forums, it just does not look like Skype are putting this high on their priority list ...

So thanks for the head's-up on the Skype client version and hopefully we'll see it sorted soon ... meanwhile, lets hope that Google do it better!!!! ;-)
 
You'e welcome :) I guess that this issue wasn't exactly easy to find, but the Skype tech I worked with indicated he had posted this since January 11 and I didn't find anything out there on this. It's nice to know there's a place to find older versions so that people can actually go there in case situations like this occur.
 
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