Cisco 1921 router working with panasonic NT phones

[barrycombined]

hi,

I have an ongoing problem with a Cisco 1921 router which we are trying to use Panasonic NT phones on.

There is a 1921 at each site, the phones register ok but we have no audio either way.

I am by the tech guys assured the relevant ports have been forwarded to the Panasonic telephone system and SIP ALG is disabled.

Anyone else come across this or a similar problem

[balaji.bandi]

Depends on your setup, show us your network topology ?

is there any NAT or VPN involved here ?

[barrycombined]

Hi balaji.bandi,

We have a Panasonic NS700 telephone system in the companies head office. This is connected to the VWIC3 card in the 1921 router. The system has SIP lines through the provider who are Spitfire Comms. These work fine both incoming and outgoing.

The problem arises on the remote offices. There we are trying to connect a small number of Panasonic NT 551 telephones which are a Panasonic proprietary IP telephone. The phones connect and register ok. However there is no speech either way.

If I try and connect the phones to another site where I know the routers are set up ok again there is no speech when connecting through the 1921 router.
I’m assured all the relevant ports are configured correctly.

After reading other user problems my concern is either the 1921 router or the Spitfire network do not support IP telephones. I’m considering trying some SIP phones to see if these work.

Thanks for any help or advice you can offer. My background is on the telephone side and I rely on networking experts to supply and configure the required routers. However on this occasion the networking company have also exhausted all those options. I am now thinking it’s a comparability problem rather than a configuration problem.

[chrihussey]

How are the NT 551 phones connected to the 1921 router?

Would it be possible to post the 1921 config as well as the output of "show inventory"?

Thanks