Onprem VOIP, Jabber, oneway audio in first 10 s when rx internal calls

[Thomas1982]

We have an on-premises Cisco VOIP system (which I find very complicated and barely understand) and are currently migrating users from IP Communicator to Jabber.

One user, out of about 100 migrated, experiences one-way audio in the first 10 seconds of an internal call they receive when the caller dials the internal number. They cannot hear the caller but the caller can hear them. The issue does not affect the calls they make, it does not affect external calls, it does not affect calls made by an internal user but dialling the full external number. The fault occurs both on the LAN and when they are remotely working connected to the (MS RRAS) VPN.

I did a test call and viewed the Jabber statistics on both ends and didn't see any dropped packets or discrepancies.

Has anyone seen anything like this before.

[MxHadi]

A one-way voice call is made in 99% of cases due to network issues.
Also, one-way audio means that one phone can send RTP to another, but the other phone cannot..

Check if there is a firewall between your phones?

(network firewall  or  windows firewall) (test it by allow voip traffics or just disable them)

And check if you do NAT between your phones?

(we must not use any NAT in voip networks..)