Problem VoiP Conversation

Unanswered Question
Jun 24th, 2009

Hello everybody,

I deploy a VoiP system based on Call Manager Express to link branch to central site.

I have a problem with a conversation :

When I call the branch, I receive and understand correctly the speaker but he doesn't. After debbugging, I see that I lost on the CME the RTP packets.

And He can't call me !!

Have you some idea ??


I have this problem too.
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Paolo Bevilacqua Wed, 06/24/2009 - 12:01

Are you using VPN / ADSL ? If so, remember that there is no QoS on the Internet. Your only remedy is upgrade the connection.

david-lima Wed, 06/24/2009 - 12:18

Hi, for one-way audio please check these points:

•Verify bidirectional IP connectivity (usually ping)

•Verify configuration parameters on H.323 gateways. Configure h323-gateway voip bind srcaddr ip address on the interface you are using for signaling.

Be sure the voice rtp send-recv command is configured on the gateway.

•Check for NAT or firewall restrictions. Be sure that a firewall (if exist) is not blocking RTP traffic.


And He can't call me !!

Verify your dial-peer voice voip configuration that is pointing to the correct device gateway/callmanager.

All the best


maxime.chevet01 Wed, 06/24/2009 - 22:31

In a first time, to answer at p.bevilacqua I not using VPN or ADSL, I work on the ISDN network between the branch but I don't think it's this.

In second time, to david-lima:

. Ping works fine.

. I put the different command and I will give you the news !!!


Paolo Bevilacqua Wed, 06/24/2009 - 23:34

Hi, ISDN with one B-channel doest have enough BW for G.711. Either use G.729, or two B channels.

Either way, ISDN is far from ideal for VoIP.


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