No Audio - PJSIP and Remote Extensions
On a fresh FreePBX installation where the PBX is directly connected to the Internet, remote extensions might have no audio. This usually happens because PJSIP tries to have the remote extensions communicate directly with each other instead of going through the FreePBX server. This would normally work if the remote extensions were connected directly to the Internet. However, most remote extensions would be within internal networks, thus behind NAT. The solution is to force remote extensions to send media through the FreePBX server. To do this, edit each extension:
Edit the extension and go to the Advanced tab.
Find the Direct Media setting and set it to No.