HELP: No Audio on Internal Calls, External calls Working fine


I am currently using FreePBX 12.0.29 with Asterisk 11.
Calls from an outside line and calling outbound works, but within extension calls have no audio.

Is there something i need to know about FreePBX 12 with regards to audio issues on internal calls?

Please help


If you need some help, you best shed some light on your installation.

No one knows your network topology.

Throw us a bone here and be as detailed as you can.

What do you have in your localnet setting?

Hi Guys,

Thank you for your interest in helping me out.
We have a FreePBX server (VM hosted on H.E.), we are using some Cisco 303 hard phones deployed in the Philippines, and some Cisco 525g deployed in the US. So basically all phone are remote to the server.

Lately, we discovered that while keeping the call active (without audio), after about 10 seconds on the call, we began hearing audio on both ends. Or if we call another extension (without audio), pressing and releasing hold button will have the audio on both extension. Only having audio issues on within extension calls, inbound/outbound calls to /from an external number is working fine.

Please attached for my network settings

Also, the following screen shots are my extension settings

Also, the following screen shots are my Asterisk SIP Settings

Hopefully, you guys can help me out resolving this issue.

Thanks in advance

Are you using NAT on internal IP’s? If so, that’s going to cause you an issue. Your phones I’m assuming have a private IP addresses on them, and you’ve most likely set NAT to yes with regards to SIP (SIP trunks, perhaps?). Your extensions NAT is also set to yes. If they’re on internal IP’s, set them to “No” and see if that fixes your audio issue.

Hi JonnyWhatshisface

Thank you for your response, appreciate it.
All our phones are using the server’s external IP, as all phone are not on the same network as the server.
Isn’t it right that NAT should be enabled in this case?


I had the same issue and we are using nat. on the sip trunk we had to set the external address to our public and then set local networks to the internal / 23 which is what we were using. try changing your local network to /24 not to say you typing it out wont work but just for kicks. also up the RTP port range to 35000 we did that as well and it seemed to work without any issues

Hi Keith Ferguson,

Thank you for your advice, appreciate that.
Will try to change the settings to what you have said.

Keep you posted guys


You blacked out a LOT of the useful info in your screenshots. Keep your public IP hidden, but private IPs are okay to share. See below for private IP ranges:

Also, I just delete the portion of the image I want hidden instead of a black line through it. Looks cleaner & takes the same amount of effort :smile: