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New Member

Cisco IP Phones calls drops behind a firewall...

Dear Friends,

I have a problem on my IP Phone communiations...

We have Cisco Call Manager 4.1 which is connected to DMZ port of PIX 515E 6.3 ver with IP address .

On the Internal Interface I have 40 Cisco 7912G Ip phones with static address of ,,all are allowed to access CCM from Internal to DMZ and i have opened all the ports.

We also have some around 100 7912G across WAN which gets registered with CCM and the communication between the external phones to Internal phones were smooth all these days.

Nowadays we are facing a peculiar problem, that all the Internal phones are getting the registration lost and it renews the registration with the CCM once we dial some number ... and the call is getting dropped... Even Internal number to another Internal number the calls are gettig dropped ...

Once call is placed this time is exactly 40 seconds on all the internal phones to loose the registration and gets registered again.

We are not facing any problem on the external phones and they are able to contact each other and calls are not getting dropped.

I dont find any problem on the Call manager as external phones are working fine with the same call manager.. I am not able to find why this is occuring nowadays..

Can any one hint me..

New Member

Re: Cisco IP Phones calls drops behind a firewall...

make sure on your pix has at least these two command.

fixup protocol skinny 2000

fixup protocol tftp 69

what I am suggest is to check pix log, good luck

New Member

Re: Cisco IP Phones calls drops behind a firewall...


Thanks but

fixup protocol skinny 2000 is already there..

fixup protocol tftp 69 i am not able to give the command.. it says that bad protocol tftp...

I am using 6.3(1) code.