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New Member

Callmanager and SRST (Wrong DN)


I have got a confusing problem! Maybe someone could give me a hint or solution for that.

On one site ?A? I have got a CM on the other site of a MPLS line (Site B) I have got a voice gateway (H323). (124-15.T1). All phones on site B are registered to the CM. And if these phones are calling someone outside it is routed trough the MPLS to the voice gateway without any problem. And if this site B loses it connection the voice gateway should go over to fallback. It looks as it would work fine. But if these phones are registered to that router they get wrong DNs.

There are 5 phones:

One phone without extension mobility.

Four phones with extension mobility.

They have got new created DNs from 2220 ? 2222. (New device pool, new partion, new ccs) One extension mobility account was an old one. (1111) Since we started this user was logged in on one phone on side B.

The CM isn?t using auto registration.

After Failover:

On nearly every phone the DN has changed. Numbers out of 65xx 64xx are now displayed one the phones. The phone where the old extension mobility account 1111 was logged in has kept its DN.

I tried to restart the voice gateway but without any change. After that I did a hard reset on one phone. (Phone without extension mobility.)

Same results on SRST ? a 65xx DN.

Then I thought it could be something with these new created DNs so I logged out the old nr (1111) from the first phone and logged it back in to the second phone.

After I tried SRST. Phone number one had again the 1111 number and the second phone had the old 65xx number.

Has anyone got a clue or a hint or much better a solution for my problem?

Thank you for any help


Re: Callmanager and SRST (Wrong DN)

Do the IP phones display 'Operating in Fallback Mode', or equivalent message?


New Member

Re: Callmanager and SRST (Wrong DN)

Yes they do display "SRST Fallback"


secondary-dialtone 9

max-conferences 8 gain -6

transfer-system full-consult

ip source-address x.x.x.x port 2000

max-ephones 28

max-dn 60 dual-line

system message primary SRST Fallback

time-format 24

date-format dd-mm-yy

New Member

Re: Callmanager and SRST (Wrong DN)

Today I downgraded the voice gateway to c2800nm-spservicesk9-mz.124-9.T5.bin and I did a reset on all phones.

Afterwards I initialised SRST. But I still get the wrong DNs.

What cause a phone on fallback to get a wrong dn?

New Member

Re: Callmanager and SRST (Wrong DN)


Did you find a solution for this problem ?



New Member

Re: Callmanager and SRST (Wrong DN)

Hello Dirk,

Sorry not till now. But I will post a msg. as soon as possible.

Have you got the same problem?

Re: Callmanager and SRST (Wrong DN)

The main caveat with regards to SRST is if you are using extension mobility with these ip phone endpoints.

SRST will provision the configuration of the ip phone as it is registered at the time with CallManager. The question is do you required the logged-out device settings to appear on the phone, or the EM settings?

For example, I had a problem with a branch CME SRST and in the instance when the EM profile was logged in this was what was provisioned within the running configuration.

This is acceptable, however if the phone was logged out, and the gateway failed to SRST then you would expect the logged out device settings on the phone. This was not the case, the phone re-registered with the EM details as this was what was provisioned already in the config.

In this particular scenario, I needed to ensure that the ip phone device settings were registered and not the EM details.

Within the Telephony Service, I configured SRST mode auto-provision none, and configured the ephone-dns and ephones accordingly. This guarantees that ip phones device configuration is what appears on the phone when it re-registers with SRST.



New Member

Re: Callmanager and SRST (Wrong DN)

Hello Allan,

Problem is that I am not using Extension Mobility, and there is no relation between the number in SRST and the number in the CallManager.



Re: Callmanager and SRST (Wrong DN)

Dirk, are you using SRST or CME SRST? Could you please post your configuration and the 'show ephone' output. Also can you advise what the DN range should be, as it is within CCM.