Lots of busy-tone voice mail on Unity mailbox

[tnatsukawa]

Hi,

My users get on their Unity mailbox lots of voice mail with a recording of busy tone. This seems to happen when a call from PSTN is forwarded to a Unity mailbox, Unity plays her/his greeting, and the caller decides not to leave a message and hangs up. Somehow the call hasn't ended, and the Unity hears the busy tone and duly records it, I think. The problem doesn't happen when the caller is another IP Phone.

When I have a call between an IP Phone and a PSTN phone, and the PSTN side hangs up the call, I hear on my handset busy tone for about 30 seconds before the call actualy ends...

Does anyone know how to fix this?

Tatsuo

[mimckee]

Sounds like you have a supervisory disconnect issue. What is your voice interface to the PSTN? Is it fxo? Sounds like you need to make sure the fxo is going back on hook when the PSTN user is hanging up. There is 3 ways to accomplish this. Most Telcos do power denial. If you telco is not doing that then you can do supervisory disconnect tone or battery reversal.

Hope this helps,

-Mckee

[tnatsukawa]

Mckee, my PSTN interface is an ISDN PRI on a Cisco 3640. I get the PRI from NTT Tokyo. How do I check this supervisory disconnect? Any hint? Thanks, Tatsuo

[mysterx]

Is this a dual switch integration with a PBX? Is there a gateway involved that might be somehow recording analog busy tone?

My experience has been that the TSP will react to a busy state on an IP line rather than record the signal; the only time I've seen Unity record busy tone is when a PBX or gateway is sending the actual analog tones to the Unity.

Scott Morgan

[tnatsukawa]

Scott,

"Is this a dual switch integration with a PBX?" No.

"Is there a gateway involved that might be somehow recording analog busy tone?" I'm not sure...

My network looks like:

PSTN----ISDN PRI----Cisco 3640----LAN containing CallManagers, Unity, and IP Phones

So do you think the problem is with my gateway (Cisco 3640)?

Tatsuo

[mysterx]

Since the problem happens with Unity out of the picture (you get the same behavior when a PSTN caller hangs up on an IP phone), so the disconnect supervision probably needs to come from the 3640.

I am not an expert on the 3640, but I would suggest searching CCO for terms like "disconnect supervision" "3640" ... this feature may also be referred to as "supervisory disconnect tone"

Here is an example of a doc I pulled up, you may be able to find what you need by using these search terms:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122x/122xt/122xt_2/ft_hdanm.htm#xtocid4

Regards,

Scott Morgan

Cisco Systems TAC

[dtessari]

Since your PSTN connectivity is via ISDN-PRI you will need to verify that the network is providing the proper disconnect message. If you watch the D-Channel traffic you will see a disconnect message form the CO. The Gateway should return a disconnect acknowledge message and the CO should, in turn proceed with the call clearing process.

The Call Manager has some pretty sophisticated dubug tools but a network protocol analyser would be most beneficial. If you are using a router as a gateway turn on ISDN Debug Event to watch a trace. You should see the normal clearing process described above.

The problem you are experiencing is odd as there really is no supervisory disconnect in ISDN. This task is performed through D-Channel messaging and is therefore not subject to the normal CO programming issues.