Cisco 7961 SIP registration issue with third party IP PBX

[Vivek Batra]

Hi all,

This is first time I have to use 79xx series phone with third party IP-PBX but facing SIP registration issue.

Seems that phone is correctly downloading the configuration file and trying to get register with PBX, but it keep sending REGISTER message continuously.

I tried some research on this and found that as phone is not using default source SIP Port viz 5060 (using 49162) however it is expecting response (200 OK) on 5060. IP-PBX is sending 200 OK on received port viz 49162. Phone may not be parsing 200 OK and hence keep re-transmitting REGISTER message.

Did you ever faced the same issue or some other suggestions to identify the issue or just know how to change SIP source port to 5060?

You can download PCAP traces, configuration file and phone GUI status page from following link;

https://www.dropbox.com/s/4pfqxsrslwaor3d/Cisco%207961%20traces.zip?dl=0

- Vivek

[Leo Laohoo]

What kind of "3rd party PABX" is this?  Asterisk? 

Is NAT &/or ALG enabled or allowed? 

[Vivek Batra]

Hi Leo,

Thanks for giving attention to the question. Really appreciate.

It is standard SIP based PBX (Matrix).

Both phone and PBX are in the same LAN.

If you closely look at PCAP traces shared by me before, phone sends REGISTER message with source port as 49162, however in via field of REGISTER message port is 5060. PBX replies with 200 OK to received source port viz 49162 and here is my doubt on. Phone might be expecting response on 5060 and hence not able to parse 200 OK, this might result in re-transmitting REGISTER message continuously.

My guess, if we can find out the way to fix the UDP source port to 5060, this may fix the problem but I am not aware which parameter in XML configuration file will need this change.

- Vivek

[Leo Laohoo]

Are you able to attach the SEPmacaddress.cnf.xml file so I can take a peek at it?  Remove the delicate items.

[Vivek Batra]

Hi Leo,

PFA

- Vivek

[Leo Laohoo]

<loadInformation>SIP41.8-5-3S</loadInformation>

Ok, this is the firmware loaded.  This means only UDP. 

<transportLayerProtocol>4</transportLayerProtocol>

Try value of "2".  

<proxyServerURL>proxy:3128</proxyServerURL>

I've never seen a value like this before. 

[Vivek Batra]

Hi Leo,

1. What do you mean by 'This means only UDP'.

2. I will check with TCP. Seems If I can change the protocol, port issue should get fixed.

3. I think this header is not kept purposefully. I will remove this.

Let me check with my customer and update you accordingly. Thanks.

- Vivek

[Leo Laohoo]

1. What do you mean by 'This means only UDP'.

I believe phone firmware 8.X supports only UDP.  9.X supports both TCP & UDP. 

[Vivek Batra]

Hi Leo,

If what you are saying is true, then TCP may not work and need firmware upgrade. Let me come back with feedbacks from customer.

In the meanwhile do you see any option in f/w 8.X (with UDP) to fix the source port to 5060?

- Vivek

[Leo Laohoo]

<sipProxies>
 <backupProxy>192.168.2.56</backupProxy>
 <backupProxyPort>5060</backupProxyPort>
 <emergencyProxy>192.168.2.56</emergencyProxy>
 <emergencyProxyPort>5060</emergencyProxyPort>
 <outboundProxy>192.168.2.56</outboundProxy>
 <outboundProxyPort>5060</outboundProxyPort>
 <registerWithProxy>true</registerWithProxy>
</sipProxies>

Try the configuration above