You were right, there was a STUN configured by default.
There is no NAT between them. No it is working.

Thank you very much! You helped me a lot.

During new test I found the following: The system: - android phone 1 - android phone 2 - iPhone all running LinPhone and connecting to the same wifi router through wifi. The Brekeke PBX connects to this router with cable. When I make call between the iPhone and any android phone the voice is ok, but ...

Hi janP! The RTP relay was on, but finally I managed to solve this. I swotched the Port mapping under SIP Server Admin/RTP from source port to sdp. The Brekeke PBX and the Linphones on an android phone and on an iPhone are connected to the same WIFI router (the server connected with cable of course ...

First it appeared under Blocked IP Address, but now it is woking. The bad new is if I make a call from one Linphone to an another one the voice is not working either from one side or from the other one.

1. Brekeke Product Name and Version: Brekeke PBX 3.2.3.6/365 2. Java version: 7 3. OS type and the version: Windows Server 2008 4. UA (phone), gateway or other hardware/software involved: Linphone/Android 5. Your problem: The Linphone(also sipdroid) is not able to register to Brekeke PBX. I tried ...