Outbound Audio Blocked on Specific Network

[Peter G W B]

Hello,

So we have recently set our 3CX phones system up at a new office, and everything is ready to go and functioning exactly how it had previously. Except for when a user is connected to our company provided on-site network.

Although I am aware that the problem is almost certainly somewhere in our parent companies firewall or network setup, they assure me that it isn't. Is anyone aware of what would cause 3CX to only receive and not transmit any audio when a user is using a specific network? As I would love to be able to point our parent company's IT team in the right direction.

Thank you in advance,

Peter G W B

 

[leejor]

Except for when a user is connected to our company provided on-site network.

So this is an issue with one user, at a specific location, or at any external location (do they move)?
Are they the only SIP device at this location?
Are they set to use STUN, or is this site using VPN?
What type of device (make/model), is being used?
Have you tried using a 3CX device, using the 3CX tunnel, at that location?

Perhaps provide additional details about this "company provided on-site network"

 

[JohnS_3CX]

Hi Peter,

There's a few things that can affect this, if you want to go in depth, you need to check:

1. Where is the phone sending the audio if you run a capture on the phone? (SDP ip and port)

2. Then IF the the audio is being sent to the right port and IP (because this could be wrong), check the network to see if it allows this traffic to reach its destination.

Any net hardware that does NAT or SIP ALG could also be altering the packets AFTER they have left the phone's NIC. So basically, you need to follow the content and route of the packets to pinpoint where the trail stops.

I think you should read this first before posting so we don't make any erroneous assumptions
https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/