If you've seen my other posts lately, you can obviously see we're having issues with CPA and dialer performance after having migrated to the SIP dailer from Skinny. This time, it relates to seeing a relatively high percentage of calls being marked as "No Dialtone" in reporting, call result 6 in the dialer detail table. We're seeing anywhere from 4% to sometimes 15% where we were seeing 0% when we were on the SCCP dialer. Can enyone explain what this call result actually relates to and what can be done to correct this if anything? I would suspect this has everything to do with CPA moving off the dialer and onto the voice gateways but I would have thought there'd be some documented explanation somewhere explaining what specific tweaks need to be made to CPA and/or what to expect when moving from SCCP to SIP....right?
This means the dialer sent an INVITE to the gateway, but did not receive a call progress message within the configurable timeout. This could be due either to issues in the network, configuration issues with the gw, or often delays in call setup from the carrier side.
There is a timer in the dialer registry that controls this: TimeToWaitForIPDialTone. I have found in all my customers so far that I had to change this timer to keep these errors in control. Set this to 10 seconds and see if the issue is resolved for you. If it continues happening you'll likely need to troubleshoot at the ISDN or network level, and possibly involve Cisco TAC.
FYI here is the Cisco technote on this exact problem and solution:
Thanks for your response. We actually worked very closely for about two months with Anuj, the author of the link that you posted above. That being said, one of the first things we did was increase that timer to 10. While the 408 cause codes dropped significantly after doing so, we still see anywhere from 5% to around 15% of calls fail due to this code. What type of configuration tweaks can we perform on the gateways? Have you known carriers to be able to correct this issue on their end? Is 5% to 15% an acceptable number when on the SIP dialer?
Don't really have a specific solution unfortunately. You can try turning down the dialer max calls per second throttle, but I would guess you already tried that with TAC. In the calls that fail, have you traced what happens from an ISDN perspective? Do you never get a call proceeding?
What I have seen that may cause similar issues, if you are dialing invalid numbers sometimes the ISDN events sent are not what the dialer expects. To see if this is the case, take a look at your Dialer_Detail logs and see if numbers that have this issue have it just once, or if the same number tends to have this issue over and over again every time. If the same numbers hit the issue every time, try calling them yourself and you may find that you get an invalid number message from the carrier.
Incidentally what I'm describing is the Call Result 2 issue you described above. The dialer doesn't receive the events it expects so classifies it as a result 2 even though it is a SIT tone. It's conceivable that similar problems could cause call result 6. Your upgrade might help with this too.
We are running 8.5(4) but are preparing for an upgrade to 9.0(4) which addresses another issue we are facing concerning SIT tone numbers being incorrectly classified under Call Result 2 when they should fall under Result 5. Does this newer version address additional 'bugs' with CPA on the SIP dialer that you know of?
The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
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