I assume that the VirtualBox host is the same Windows 10 machine that is running Linphone. If not, please explain.
Confirm that the VirtualBox VM is using Bridged Networking. If you type
ifconfig
from a shell prompt on the PBX, you should see for your (virtual) Ethernet interface, something like
inet addr:192.168.123.7
This is the local IP address of your PBX.
And if you type
ipconfig
at a command prompt in Windows,
you should see for your (real) Ethernet interface or bridge, something like
IPv4 Address . . . . : 192.168.123.4
This is the local IP address of your Windows machine. Both should be in the same subnet.
Now, in Linphone, set up something like
Adresse SIP* "yoannB" <sip:[email protected]:5061>
Adresse du serveur SIP* <sip:192.168.123.7:5061;transport=udp>
Replace 4840 with the extension you set up in FreePBX.
Replace 192.168.123.7 with the actual local IP address of the PBX.
Replace 5061 with the value of “Port to Listen On” (if you set up a pjsip extension) or with the value of “Bind Port” (if you set up a chan_sip extension).
If you still have trouble, report what, if anything, appears in the Asterisk log when Linphone attempts to register.