Slow 'Answering' phase during call setup

[Steven Howes]

Hi,

We're facing a problem with SPA 50x series phones. When a call is being answered by the 504 (in this example) the states displayed on the screen are:

Ringing

Answering

Connected

And the problem we're facing is the 'Answering' state tends to last about half a second or so. Some of our more quick-handed customers are able to pick up a call and say 'hello', managing to cut off all but the 'o' because the 'Answering' state is hanging around too long. I've managed to record this on video:

slow.3gp

Interestingly, this doesn't happen on the older SPA962, or the SPA525G2, so I'm guessing these handsets are faster / handle call setup differently:

fast.3gp

The 504 and the other phones are all talking to the same PBX, are all using SIP UDP, are all given the same configuration options. I've checked packet traces and there seems to be no delay there (i.e. the ok / ack packets have no delay between them). Given the PBX was common in all of these, it can effectively be ruled out. The problem is easily reproducible. Could it be the SPA50x series phones are being delayed by something?

I'd be interested if someone could try and reproduce this, or anyones thoughts on the subject.

Thanks.

Steve

[Patrick Born]

Hi Steve,

I'll set up an environment in my lab and attempt to reproduce.

Please confirm the version of firmware running on the SPA504G.

Thanks,

Patrick

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   Patrick Born | Technical Marketing Engineer (TME) – SPA SIP Endpoints
           Use this reference document to locate SPA phone resources

[Patrick Born]

Hi Steve,

I've tested SPA504 and SPA525G2 phones running 7.4.9 which are registered to an Asterisk 1.8 server.

I don't see anything like your slow.3gp video shows when calling between my phones.

Please contact the Small Business Support Center and open a case with them. I'm thinking that there may be something unique to your environment or your SPA5xx configuration. I can't explain why the SPA9xx phones do not present the same issue though.

Regards,

Patrick

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[Steven Howes]

Hi Patrick,

Thanks for checking. We've tried every firmware version listed on the Cisco site. Present in all. As you can't reproduce on Asterisk 1.8 (coincidentally matches one of our test environments) I'll get some more detailed info and try setting various settings back to default until the behavior goes away. If i find what's causing it (or indeed don't) I'll post the results here and contact the SBSC. Is there an email address for the support centre? I often think problems like this are better explained in writing, where I can attach useful information.

Thanks again.

Steve

[Patrick Born]

Steve,

I'm not in the support group so I can't provide specifics. The SBSC takes calls, provides you with a ticket number and at that point will provide a way for you to send details and attachments in via email.

Some things to try and help you gather information:

1. Make a *very* simple configuration file for each phone under test. Less is more when it comes to configuration files. Here is a document that describes a way to build a minimal config file:

https://supportforums.cisco.com/docs/DOC-13031

2. Upgrade the phones under test to 7.4.9 available from here:

http://www.cisco.com/cisco/software/navigator.html?mdfid=282733326&i=rm

3. Factory default the phones under test and allow them to pull the config file built in step 1.

4. Test to determine if the Slow Answer phenomenon still exists. If so do the following:

4.a Enable debug level 3 on the phones:

https://supportforums.cisco.com/docs/DOC-9934

    You do not need to configure a syslog server because Wireshark will capture all the debug/syslog output.

4.b Set up a computer running Wireshark on the same subnet as the phones. Use a hub or configure a port on your network switch as a port mirror [span] target.

4.c Start Wireshark

4.d Reboot all phones

4.e Run one test that causes the SPA50x phones to demonstrate the slow answer

4.f Run one test on the SPA9xx phones to demonstrate the absence of slow answer

4.g Stop Wireshark and save the trace

4.h Save the configuration from each SPA50x and SPA9xx phone under test:

https://supportforums.cisco.com/docs/DOC-14083

5. Submit the Wireshark trace and each phone's configuration to the SBSC agent that is assigned to your case.

Please do share any findings, positive or negative so we can learn or improve our phones.

Regards,

Patrick

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[k.perriere]

Hello !

I have the same problem with 12 SPA504G with a UC320.

I am french and I am sorry for my english, but I don't know what to do with this problem ...

We have try with and without the charger : it's the same !

We have change the QoS, the UC320 and it's the same probleme.

Restart everything,

Help me please.

Thanks

Karen