One way audio on first call

Unanswered Question
Mar 8th, 2010
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I have a setup with a SPA9000, SPA400 and several phones (962,942 and 922). All phones and the 9000 are flashed to firmware 6.1.5.

My problem is that after some time (didnt figure out how much time) outgoing calls only have one way audio.

I can hear the other party fine but they can't hear me.

The second call (redial) within seconds always works fine.

Incoming calls are fine.

Internal calls are OK

The SPA9000 works as a gateway (Force Media Proxy = Yes) and registration is fine I think (register expire = 3600, just like my provider states) and connection is being made right away after dialing.

My thoughts;

  • No firewall issue because second call succeeds
  • No codec issue because second call succeeds
  • No hardware issue because more phones have the same problem

The 9000 is directly connected to a router/firewall which has been replaced with another brand without improvement.

The phones are connected to a managed Nortel PoE switch

Any suggestion is welcome :)

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Alberto Montilla Tue, 03/09/2010 - 05:45
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  • Cisco Employee,

Dear Sir;

On Line 1 (SPA9000) please set NAT Keepalive to Yes. This looks like a UDP port closed issue.



gwankho Tue, 03/09/2010 - 22:44
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Thanks Alberto,

Changed the NAT keep alive to YES and will see if the problem reoccurs.

Will keep you informed.


gwankho Sun, 05/16/2010 - 02:43
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Tested for a long period to make sure.Two way audio every single time :).

However my provider upgraded also my modem/router to a total new box (was Thomson, now I got a Fritzbox 7170).

So I'm still not sure which one solved the audio problem.




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