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Beginner

7945 doesn't work but 7940 does over DMVPN connection

Hi, I currently have a DMVPN connection to my office and bought a 7945G phone for my house. This phone works great in the office, makes and recieves calls. I bring it home and I get 1 way voice where the end user can hear me but I cannot hear them. Routing has been verified and is working correctly. I brought home a 7940 phone from the office to test my configuration and was able to get inbound and outbound calls to work correctly.

This leaves me with an issue with the 7945 phone. Has anyone else hit this issue before?

Both phones register with call manager and I am able to use features suck as ext mobility on both. I also get dial tone on both phones

I can provide any configuration needed, packet captures, and debug information.

Thanks in advance,

Chris

7 REPLIES 7
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Cisco Employee

Are you doing any kind of NAT with the VPN?  If so what are the firmware versions on the 7945 and 7940, they may be running different SCCP versions which can lead to audio problems since some network devices cannot inspect certain (mainly newer) SCCP versions to NAT the addresses inside the SCCP packets.

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The 7945 is running SCCP45.8-5-3S

The 7940 is running 8.1(1.0)

Sorry if I am off, I am a Route Switch Security guy more than I am phones.

Do you think a lower firmware version on the 7945 would work? Or at least be the next step in troubleshooting?

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Hi Chris,

Do you find a solution for your problem?

I have the same issue

Thanks

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Hi there,

I did find a solution. The phone was converted to SIP and a new CSS was created as outbound calls are delayed 10-12 seconds by default. Make sure you have DNS pointed to the main location and also have a DNS prefix set as there is a lot of java running on the phone.

I found wireshark a great tool to troubleshoot and see whats happening.

Let me know if that works for you. I am the only user at my company doing this so far, but others are going to join justing waiting on gear to get in.

Thanks!

Chris

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So,

Finally with SCCP the 7965 does not work, just with SIP ?

Thanks

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I have only tested a 7961 partially, I did not get a chance to convert that to SIP, but it did not work as a skinny phone. I would assume any phone that runs a newer skinny and needs to work over DMVPN with natting needs to be a SIP phone.

I am interested to hear your results though.

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Hi,

I did my tests with ip phone 7945, with SCCP no works and with SIP yes !!!

Thanks for your help..