No audio between extensions

[joshuao3]

Hi! I have 3cx almost up and running. If I can get one last thing working then I'll make the purchase. Here's my config:

3cx FREE on AWS
Firewall checker says we are A-ok
2 phones at home office, both Grandstream GXP 2000

Inbound calls work perfectly from the outside (I use callcentric to provide the trunk). I can hear the caller and they can hear me. I can hear sidetone on the handset, etc. All seems ok.

Problem:

Calls between extensions ring, but when answered there is no audio either direction. There is also no side-town in the handset.

Any ideas??

Thank you.

 

[leejor]

Post a 3CX log of a call between extension, or at the least review the log to see if something stands out. You may need to set logging level to Verbose to have anything helpful show up.

AWS... Amazon Web Services?...so the sets are remote, to the PBX? You may have to give each a unique port number, and see if that helps. You may also try enabling PBX Delivers Audio (per extension). Not the best option to leave enabled, but it might help pin-point the problem.

 

[joshuao3]

I will try these ideas and let you know. Thank you for your willingness to lend a hand!

 

[joshuao3]

PBX Delivers Audio fixed the issue. However, both extensions are on the same LAN, so it seems weird to me that this should be necessary. Do you think I should focus my attention on the phones or the PBX to look for a long-term solution?

 

[joshuao3]

I think I need a better understanding of what happens behind the scenes when the extensions connect.

Assumption 1: I have two extensions at the remote branch, both sitting behind the same NAT. The PBX is in the cloud. When Ext 100 calls Ext 101, it notifies of the PBX of the call and then the PBX rings the other extension. From the PBXs perspective both Ext 100 and 101 appear to be at the same IP (the public IP of the NAT), but different port.

Am I right so far?

Assumption 2: After Ext 101 picks up the handset, the PBX tells each extension the other's IP address and says, basically, "Ok, you guys go ahead an communicate and let me know i you need anything or hang up". Then, it tells each extension the other's IP address and port.

Am I still correct?

Assumption 3: This isn't working because the IP address that the PBX knows, which is the NATs public IP, doesn't really mean much to the phones because they both have local IP addresses. Regardless, each phone tries to send audio to the IP address that the PBX told them, but the router is just dumping it because it doesn't know what to do with the traffic.

Am I understanding the problem correctly?

Is there a way to tell a phones to talk to the other phone's LAN address instead?

Thanks.

 

[SY]

Please check
http://www.3cx.com/blog/docs/media-server/
There is description how media delivery works.
"PBX delivers audio" option can solve the problem.

Regards