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Cisco 6921 phone configure to 3cx

Danushka

Bronze Partner
Advanced Certified
Joined
Sep 4, 2025
Messages
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Dear Team ,

I am trying to configure a Cisco CP-6921 phone with the 3CX system. I am using a TFTP server on an Ubuntu machine. The phone is running SIP firmware version 9-3-3-2, but the device is not registering.
I have also used an XML configuration file (shown below) and attached the log file for reference.

Could you please review this and assist us in resolving the issue? If there are any dependencies or prerequisites required for configuring this phone, kindly let us know.

Phone Mac and file name - SEP54781A6A273E.cnf.xml

<device>
<deviceProtocol>SIP</deviceProtocol>

<devicePool>
<dateTimeSetting>
<name>GMT</name>
<dateTemplate>Y-M-D</dateTemplate>
<timeZone>GMT Standard/Daylight Time</timeZone>
<ntps>
<ntp>
<name>172.25.30.69</name>
<ntpMode>Unicast</ntpMode>
</ntp>
</ntps>
</dateTimeSetting>

<callManagerGroup>
<members>
<member priority="0">
<callManager>
<name>172.25.35.100</name>
<ports>
<sipPort>5060</sipPort>
</ports>
<processNodeName>172.25.35.100</processNodeName>
</callManager>
</member>
</members>
</callManagerGroup>

</devicePool>

<sipProfile>

<transportLayerProtocol>2</transportLayerProtocol>

<sipProxies>
<registerWithProxy>true</registerWithProxy>
</sipProxies>

<sipLines>

<line button="1">
<featureID>9</featureID>
<featureLabel>1001</featureLabel>

<proxy>172.25.35.100</proxy>
<port>5060</port>

<name>1001</name>
<displayName>1001</displayName>

<authName>oCIZy8ybdn</authName>
<authPassword>9vtHEHxFTL</authPassword>

<contact>1001</contact>

<autoAnswer>
<autoAnswerEnabled>2</autoAnswerEnabled>
</autoAnswer>

<callWaiting>3</callWaiting>

<maxNumCalls>2</maxNumCalls>
<busyTrigger>1</busyTrigger>

</line>

</sipLines>

<preferredCodec>g711ulaw</preferredCodec>

<dtmfAvtPayload>101</dtmfAvtPayload>
<dtmfOutofBand>avt</dtmfOutofBand>

<startMediaPort>16384</startMediaPort>
<stopMediaPort>32766</stopMediaPort>

</sipProfile>

<loadInformation>SIP69xx.9-3-3-2</loadInformation>

</device>

Thank you .
 

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Hello Danushka,

There will not be any support to get this IP Phone working on the 3CX.

Please focus on why the phone does not register.
Try things like:
- Factory reset phone
- Provisioning the phone (i guess that this will fail again)
- Enter the phone web-interface and check registration
* once you know what is the problem, why it could not register, and what you need to do to get this working, from that moment you can add/change this in the XML file for registration.

However, personally I do not think that this will work at all, not because of this specific type IP Phone, but just general Cisco.
Anyway, you can try to get it working, where you should focus on getting it to work first from the webinterface before any provisioning can be done.

Paulo
 
I can't help you with this specific model or cisco in general.

But I would recommend you to increase the logging inside 3CX to debug (maybe this can tell you possible problems). And look if you see traffic from the phone at all (sometimes everything is correct configured but firewall or routing problems happen in between). You should also try to record PCAPs on 3CX.

Maybe you can see something odd.

And while you try to connect new unsupportet phones I would whitelist the IP address of the phone.
Cause if you play with different settings 3CX may blacklist the IP in the beginning and all your tests are useless if 3cx blocked the phone IP with the first failed logins.

Hope this helps you a bit.
 

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