Outgoing and incoming calls failing periodically (T1/PRI)
We're continuing to have a problem which we think is on the provider's side (isn't it always?). However, they keep pushing back on us and telling us they don't see anything wrong with their equipment. They'll admit they see the B and D channels dropping and resyncing (I think that's the terminology they use but I'm not a Voice guy) but all of their interfaces are clean. The problem lasts for 5-10 minutes and happens sporadically. It may happen 3 times 1 day, and not happen again for a week. It's starting to happen more frequently though. Anyway, here are the facts:
Outages last for 5-10 minutes
Internal (on-net) calls work perfectly fine
Outgoing/Incoming calls fail
We use Solarwinds, syslog and RTMT to monitor our systems
None of these have indicated we have a problem internally (ie no alerts generated during outages)
TAC deduced the problem was with our network or the provider since calls aren't making it to CUCM
Create a T1 loopback plug and then plug it into the T1 port. Run debug isdn q921 output & check if the SABME was sent
this message received should be:
RX <- BAD FRAME(0x00017F)Line may be looped!
The BAD FRAME messages indicate that the router performs correctly. The router sends out the SABME packet. The message is looped back to the router, because of which, the router receives the same SABME message that was sent. The router marks it as a BAD FRAME, and presents the error message. The error message states that the line is probably looped. This is the expected behavior for the looped circuit. Therefore, the problem lies within the Telco ISDN switch or the cabling from the demarc to the Telco switch.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.