Call drop out no errors\warnings

[Peter Longley]

We have been having various intermittent call drop outs when placing outbound calls.

A total of around 17 people are using the SfB Cloud PBX solutions to make PSTN calls outbound and randomly a call will drop out for somebody with no warning or error.

The other users will still be on a call and it is happening to any of the users intermittently.

Support have no idea so far.

My concern here is that we are planning to put the other 40 users over to this as our main system but do not want the issue to continue for those as well.

Our internet connection is solid and at 200MB up and down on a fibre circuit.

Surely there needs to be a reporting feature in the background for support to be able to see what causes a dropped call...

[#2]

Hi

There is some troubleshooting you can perform your side. On a client that has experienced this issue grab the UCCAPI log from %localappdata%\Microsoft\Office\1X.0\Lync\Tracing folder and use Snooper from the Skype for Business Server Debugging Tools https://www.microsoft.com/en-us/download/details.aspx?id=47263 to parse the log into system and SIP messages. Find the problem call and see what errors are coming back.

You may find it could be a SIP problem, it could be a restriction of somekind maybe on the firewall if SIP ALG or DPI has been enabled for instance. Could be a NAT issue, all kinds of things. 

You may need to get wireshark out too.

If your users use a Web Proxy Server for internet access, this can also affect Skype Online

Basically you've got to be sure that it isn't your environment that is causing it. Microsoft support can only help if the problem can be identified within their network and cloud, and the chances of things being their fault are probably lower than the chances of it being some kind of nuance in yours.

[#3]

You could try using "Call Analytics & Call Quality Dashboard" 

https://techcommunity.microsoft.com/t5/Skype-for-Business-Blog/Introducing-Call-Analytics/ba-p/57309 to find out possible root cause of the issue. 

Mark's advises are very helpful too to narrow down, and finally pinpoint the root cause of random calls drop.

[#4]

Are the calls dropping from a home network, or only while connected from within the office network? If the calls are only dropping while connected from within the office, then I would look at the firewall's settings and contact the firewall vendor's support team for assistance. Also, does it make a difference if the clients are connected via wifi or wired?

 Microsoft recently updated the minimum TCP/UDP egress port requirements (June 12, 2017), so double check that these ports are allowed out to the internet:

TCP 443

UDP 3478, 3479, 3480 and 3481

reference article is here