RTP packet does not reach right IP address



I have just been forwarded a problem from a company that we provided with two Grandstream phones - one GXP1628 and one GXP2160. While GXP2160 works fine, GXP1628 does not seem to send any sound when calling. Problem is that the RTP packet stop (or reach) at the wrong IP. I am attaching a picture of communication: the upper one is GXP1628 and the lower one is GXP2160.
Thank you for your help.


Check Invite and 200 OK SDP section for media server.
This screen do not show anything usefull.


I am sorry but this is all we got from our client.


It seems to me that the RTP flow on the photos is there both in the outward and return.

try to exclude codecs, it seems strange to me to use both PCMA and G729


The codec is not strange, one device has g729 as the first priorty codec in its offer, but the other device at X.X.1.4 only elected g711a and that is what they negotiated to use.

But as Marcin indicated, without the details of whats in the flow, no way to know. The 1628 is in a different subnet and we no nothing of the network setup as well. The 2160 is in the same subnet so RTP should not be an issue.