Here's a reader question that I can only begin to address

Hello Ken,

I am a Network Engineer with a company called [deleted for discretion].  We have implemented VoIP in our environment but have a question on Call manager and having Unity Voicemail off site.

Currently we are experiencing voicemail prompts that are garbled, the message the user leaves is fine if they hold on through the mess and hear the tone to leave a message. I have been working with Cisco and Berbee to figure this out but need some help

Outside caller calls in to our system through PSTN network gets routed through the WAN to a Unity server located in our main datacenter. The Greeting and prompts are garbled. But does not happen every day.

Any Ideas what I can check?

I've worked on a variety of Call Manager deployments using Unity Voicemail. I have to say I've never encountered this particular problem. I reached out to a couple of contacts who work in that environment, and they haven't seen it either.

Based on no firsthand experience, I'm sharing their conjecture and mine with some ideas where to perhaps look.

The fact that the prompts are garbled, but voice mail is not, seems to point at Unity itself. The architecture of the implementation isn't known, and topology could be a factor. It sounds like the quality issue (garble) occurs between Unity and the caller.   I'd look into the network between Unity, the PSTN gateway, and the link to the PSTN. Garble isn't clearly defined, but I'm guessing you're experiencing high packet loss, latency, jitter, or a combination of those on the portion of the link between the Unity prompt message and the caller. And since messages seem to work fine.

I'm prompted to ask whether the Unity system that sends that greeting and the host system with the hard drive storing messages are on the same server, or the same network segment, The fact that this problem occurs in greeting playback, but not messages left indicates that there's some difference in network traffic parameters between those two - that they take place under different conditions. I think that's where I'd start.

This question came in on the VoIP Community, but I'm posting both there and on the blog in hopes that others may have seen this situation before and have some thoughts to add.


Technorati Tags: Cisco Call Manager, Unity voice mail, VoIP, reader question