We seem to have a fairly stable Cisco VoIP implementation with a high rate of calls without issues (that is good).
However, the few calls that do get dropped are almost always a "origCause" code of 41. The only documentation I can find reports this as a "Temporary Failure" and that I should "try the call again immediately" (that is bad).
On a percentage basis, it's a very small amount. But for those groups who migrated from PSTN--with no random drops--even a single drop gets escalated up the food chain.
Yes, it's true that it is temporary, and trying again goes through without issues...but does anyone have more details on what may be the cause? I can't seem to correlate any other issues system-wide, network or phone related.
I'm just looking to see if anyone has tracked down these issues and what they were, or if someone could point me in the right direction.
You should mention who originate the failure in first place.
If telco, blame them.
Some legacy can PBX appears to not fail simply because they retry on failure. Cisco doesn't.
For the calls that dropped, were they inbound or outbound calls? Basically, what was the origination device, IP Phone, gateway, etc...?
You can look at the CMR informaiton, if it exists, to see if there were a lot of dropped packets in any direction. It could indicate a network issue between the two ends.
In my experience, cause code 41 indicates either a network/QoS issue or a flapping PRI channel.
Thanks for the replies.
Almost all (>99%) of the cause 41 calls are completely internal within the company (on a large network with 1,000s of end users)...although they appear to all be crossing between our UC callers and our legacy Avaya system--that is, they are not UC to UC.
About 2/3's are originating drops, and the remaining 1/3 are destination drops.
Paolo -- thanks for the info on the retries. I was not aware of that. Is that the default setting? Can it be changed?
Adam -- I'll have to look at the legacy PRI, attention has been focued on UC since, you know, it's the new kid on the block.