Audible Carrier Error (Call fails but no SIP error)

[DanH]

Hi all, here's another throwback from last week, boy am I playing catch-up here or what! This is a good one, once a mystery with much head-scratching at inconclusive call logs, this problem takes us back to our roots and some of the lessons we've learned along the way with configuring KAZOO and getting it to play nice with carriers. What follows is the description and steps taken to resolve it, a configuration error at its core. 

There once was a client, and they couldn’t make outgoing calls. They wouldn’t get a SIP error in these failures; looking at the logs you wouldn't see any error or any kind actually. Callers were getting an audible error, coming from the carrier evidently. KAZOO didn’t know the call didn’t complete because there was no SIP response indicating such, and KAZOO thought the call completed. When the support team was investigating this, no stone left unturned, a surprising revelation unfolded: it turned out to be Caller ID settings. You have to have a Caller ID number for calls to be handled by the carrier correctly. Older versions of KAZOO didn’t differentiate CIDs and numbers essentially. What was found was that when investigating CID settings on the outgoing number, the actual number was in the CNAME section, and the "CID number" section was blank. Normally, you won’t see it like that, normally it would say “none” or some string the user had input, not a blank field. The completely blank field doesn’t exist as a configuration possibility anymore, this is something that will likely only present with old configurations on old instances of KAZOO.

Here are the steps to resolution the team came up with: 

• This applies to situations in which a User has an outbound Caller ID that was set in an older version of Kazoo:
  • You will receive a carrier message along the lines of “Call could not be completed” on the audio channel, yet the logs don’t show the call being rejected. This is because as far as KAZOO is concerned, the handoff to the carrier was completely successfully, and it’s the carrier’s own requirements after that handoff that cause the call to fail.
  • This happens because Kazoo doesn’t know that the audio you’re hearing is a rejection message due to the carrier not sending a SIP response that indicates the call was rejected.
• To check/fix this:
  • In Advanced Callflows, go to User, select the User in question, and then click the Advanced tab.
    • From here, check the Caller ID tab and look under Outbound Calls.
    • If this was set in an old enough version, you’ll likely see that the Caller ID Name is set to the number you wanted to use, but the Caller ID Number will be totally blank rather than saying “None”
    • Simply change this by selecting the proper Caller ID Number.