I have been troubleshooting an issue where we see issues with DTMF recognition on out IPCS (GVP 7.6, no RM, SIP Behind). What we see is that a number like 123456789 will be recognized as 12234789, 1233456789, 124789, 1123455689. Notice that in some cases one or more of the digits are duplicated. In other cases digits are missing. And in other cases, digits are both duplicated and left out.
Wireshark tracing of the rtp stream suggests that the length of the dtmf tones varies. In some cases the tone appears to be less than 10ms. Based on this we adujusted the dtmfminduration parameter in the IPCS ini file from 0ms to 50ms. However, this did not have a positive effect.
Two other important items are that the issue occurs under minimal load as well as heavy load. I have redued data down to a percentage and we see a consistent 11% to 15% of our calls experience the issue. This includes weekends where the call volume is 1/10 of a week day.
The second item of interest is that we are still running our old GVP 6.5.4 In Front platform and the calls that are processed there have never exhibited this issue in 3 years. But as soon as we migrated the first client to the GVP 7.6 platform, that client had the issue.
Also, we have confiured QOS, the machines are physical, not VM, they are 2 pro, dual core Intel with 2 GB. On a busy day about 100 calls are active. The calls are processed against about 25 different IVR apps. Most apps are DTMF input only. A few have 1 or 2 speech rec inputs that are handled via MRCP to SWMS/Nuance 3.0 server.
One hope I have with this post is that someone has a document that explains the options found in the gvp.ini file. In particular the MCU and MCU_NativeRTP sections.
Thank you for the help.
