atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems VRS in TOPAZ System

Dear All ,

I have a strange problem with VRS in TOPAZ system concerning there is no DTMF once the call enter the VRS and the caller try to dial the extension there is no DTMF and there is a silence

I made the loop test between extension and trunk port and ringing to this ext the VRS answer and i can dial any internal extension , that is mean there is a problem between PSTN provider and topaz system concerning on DTMF there is no synchronize

I have tried call with provider to help me but there is no results , Is there any command on topaz to adjustment the DTMF on the system or can any body guide me to solve this problem ?

The Topaz has the worst DTMF receivers in the world. They should never have gotten certification. Below are the DTMF receiver settings we use. It solves about 90% of the problems we get here..

Here are the recommended DTMF Detection settings for Topaz.

80-03-01: DTMF Detect Level = 0
80-03-03: DTMF Minimum Detection Level = 10
80-03-04: DTMF Maximum Detection Level = 5
80-03-05: DTMF Forward Twist Level = 4
80-03-06: DTMF Backward Twist Level = 0
80-03-07: DTMF ON Detection Time = 2
80-03-08: DTMF OFF Detection Time = 1

Should the customer experience false DTMF detection during VRS/VMS messages:
1. Reduce the twist level (80-03-05/06) to a minimum of 2/0.
2. Fine tune the detection levels (80-03-01/03/04).
o Narrow the range and/or move down in level using 80-03-03/04.
o Reduce the level range 80-03-01 from 0 to 1, then repeat above step.
3. Reduce the playback level in PRG 40-10-06 to around 20 to 25. Less if possible.  Reduce as low as practical (around 20).
4. Rerecord the messages using a deeper male voice, this is less prone to talk off.

Should the system be unable to detect DTMF digits while dialling during VRS/VMS messages:
1. Increase the twist levels (80-03-05/06) to a maximum of 9/9.
2. Slowly widen the detection range (80-03-03/04).  Set to 15 and 0 respectively (widest range)
3. Increase the detection level to a maximum of 80-03-01 = 0.

Note that there is balance between countermeasures for false detection and missed detection of DTMF signals. Fine tuning may be required to address both.