We have a customer that has a centralised call proccessing deployment. When IPT calls are made between location A and location B the audio quality is fine, using G729, but when users at location B access Unity vmail, which is housed at location A, the audio quality is very poor. If we up the codec to G711 the quality is fine.
Has anyone got any ideas as to why IPT calls would be fine but Unity calls are poor, both using G729?
AGC and/or QoS could have an impact on remote g729 calls and impact voicemail in different ways than phone-to-phone.
First consider what part of the conversation the callers from site B are unhappy with. Is it the Unity prompts that play out message counts, etc? Or is it the actual messages that are being recorded? Since prompts aren't often an issue, let's consider the recordings only.
If you have Unity version 3.1(3) or later, we have a default 'Automatic Gain Control' feature that alters incoming recordings to a target decibel level. Without getting into the details, g729 recordings could sound 'different' than phone to phone g729 calls because of the gain applied or any transcoding event that AGC uses. To disable AGC, use the "Advanced Settings" tool from the Tools Depot.
You should also consider QoS for calls to/from the remote site. This will ensure the original call is as clear as possible. This doesn't have any specific impact on Unity-Site B calls, but might give all calls priority over the link.
It is the Unity prompts that are of poor quality. I have not set up the system but have been reliably informed that QoS is setup across the WAN. We have had no complaints about phone to phone quality.
As for disabling AGC, I don't seem to have an option for this in advanced settings (we are running ver 4.0). What we do have is , Sample size (20000), Gain Threshold (40), Adjust volume target level for new recordings (-26) and Minimum dB threshold (45). Is this important though if it is the Unity prompts that are poor quality?
Apologies, I am getting my customers mixed up. This particular customer is running 3.1(5).
How would I check to see what prompts are loaded in 3.1(5), plus if I loaded the G729 prompts as you suggested, would that mean the region that Unity resides would use G729 as well, or only the remote regions?
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