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New Member

IP phone 7940 constantly rebooting after swapping router

Hello,

Not quite sure if this is the right group but we are experiencing some weird issues with the VoIP phones after swapping out a 1700 series router with a newer 2821 router.

What is happening is that the 7940 phones keep rebooting or just not allowing users to answer a ringing phone.

The configuration is the same on the new router as the old router and there are no errors reported by the router or switches.

Any ideas on why this may be happening?

On the original 1760 router there were no problems.

Also upgraded the IOS on the 2821 to the latest version and that didn't seem to help.

Cheers,

- Trevor

13 REPLIES
Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

Check phone FW, may be old and fighting with new IOS/CME.

New Member

Re: IP phone 7940 constantly rebooting after swapping router

Hi,

Thanks for the reply.

What do you think would be causing the phone FW to be conflicting with the router IOS?

Cheers,

- Trevor

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

CME is like that. You should observe the boot phone process and determine what makes it fail.

New Member

Re: IP phone 7940 constantly rebooting after swapping router

Problem is that the phone boots fine and the issue is intermittent.

Seems sometimes that the phones will work fine and at random the phones reboot or a call not be able to be answered.

Cheers,

- Trevor

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

Probably old buggy phone FW and you should upgrade it.

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New Member

Re: IP phone 7940 constantly rebooting after swapping router

Well we upgraded the phones as we were in fact using the older model and FW.

But now it seems that everynow and then the phones will re-register to the network (No rebooting so far).

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

Check if any rogue DHCP server on the wire.

New Member

Re: IP phone 7940 constantly rebooting after swapping router

Nope no rogue DHCP servers on the wire.

Just found out this afternoon that the phones will seem to lose connection to the call manager and display something like "cm fallback service operating" and no dial tone so basically have to do a reboot on the phone to get it to re-connect to the CM.

Could be that the connection is over a wireless bridge? But that doesn't make sense as the phones were working fine with the 1760 router.

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

Which exact IOS, and which exact phone FW ?

New Member

Re: IP phone 7940 constantly rebooting after swapping router

On the 2821 router we are using 12.4.25b and on the VoIP phones, using FW SCCP41-8-4-3S.

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

CME 3.3 ? Check with show telephony.

That is not even supposed to support the 7941. or do you have 7940 ?

Recommend you upgrade to something like CME 4.1 minimum

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/requirements/guide/33matrix.htm

New Member

Re: IP phone 7940 constantly rebooting after swapping router

The phones are 7941. If you are refering to the call manager version, we are using CUCM 7.0(2)

Hall of Fame Super Gold

Re: IP phone 7940 constantly rebooting after swapping router

Are the phones on a different subnet than the CM ? What is the physical setup ?

Are you using DHCP server, if so where ?

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