One way audio over VPN (Except for CIPC)

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Jun 11th, 2012
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Hi all,

We are facing a one way audio problem using Cisco 6961 over a VPN tunnel.

Not NAT is used. The ipphones on the remote site can't hear the users from the HQ where the CUCM is deployed.

The stange thing is is working fine when we use IP Communicator softphone instead of the hard ip phones.

Both (CIPC and 6961) are in the same subnet .

Any idea is welcome.

Thank you in advance

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Youssef Aoufi Mon, 06/11/2012 - 08:30
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FYI we are using gateprotect firewalls on both sides of the tunnel and all tcp/udp ports open.

Brian Meade Mon, 06/11/2012 - 09:58
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I would look into getting Wireshark captures of each side of the conversation during an CIPC call and then for a 6961.  Look for any differences between the captures.

Mohammed al Baqari Mon, 06/11/2012 - 12:20
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    2017 IP Telephony

I believe you are having two vlans for voice and data. Your desk phones are in voice vlan. CIPC will use data vlan.

If this is correct, then below are some points:

1. Make sure that your voice VLAN subnet is part of your VPN interesting traffic.

2. From your desk phone's default gateway (which is probably a router) initiate a ping to any remote phone. Use the source interface as your phone's default gateway. For example:

ping ##remote phone IP### source ###Phone's default gateway###

Youssef Aoufi Mon, 06/11/2012 - 13:53
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Hi mohamme

Thanks for your answer. I have only one vlan for voice and data. Both pc and ipphone are on the same subnet.


Mohammed al Baqari Tue, 06/12/2012 - 01:47
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- Try to ping your 6961 phones from your gateway route.

- I am assuming that both sites are registered to same cucm. What codec is configured.

- Trust point relay is enabled or disabled on phones.

Sent from Cisco Technical Support iPhone App

Youssef Aoufi Tue, 06/12/2012 - 02:13
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Hi Mohammed,

-Ping is sucessful from the HQ to the 6961(remote site).

-Both sites are registered to the same cucm .For test, same region , device pool codec is configured for both sites.

-No trust point relay is configured .

Best regards

jonathanvega Fri, 10/02/2015 - 15:01
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Hi all:

I have one way audio on a vpn connection between remote officers and my central cisco ASA , in a fourum we found that the following line can be the problem on the 5500:


policy-map global_policy

 class inspection_default <<<<<<<<<<<<<<< removing this line

  inspect h323 h225

  inspect h323 ras


What do you think about?





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