I have followed the setup instructions for secure SIP on the 3CX web page and most devices seem to work properly, but I am having major issues with the 3CX clients using secure SIP. Here are my issues: 1. Windows Client When used as a softphone, the client cannot connect. However, it connects just fine in CTI mode. Looking at the logs, it seems that it isn't even trying to connect. 2. Android Client This one connects and it shows as "On Hook", but I cannot make calls and fails with "Call failed, unavailable". I am also having another issue which might be related to this problem: Phones that are enabled to use secure SIP can receive and make trunk based calls just fine, but calls between extensions are failing with "No Media". In my network, 3CX is hosted at an external site. We initially had an IPSec vpn connection to directly connect to the 3CX system, but this resulted in less than stellar audio at times. So, we opted to setup the phones as external extensions which really improved audio, but it seems to cause issues when we are making calls from one extension to another. Any help is appreciated!