Too much loss on the phone lines coming into the Quintum gateway is the culprit.
The DTMF tones are too weak to be detected when the lenght of the tones is too short, or the level is too low.
There are gain settings that you need to tweak in order to get those tones detected properly.
Do not overcompensate the gain, because you may start having echo and noise. Do not chnge more than a couple of DB at the time.
Line
—-
Line: 1
Law = uLaw(0)
Rx Gain = -4dB
Tx Gain = -2dB
Line: 2
Law = uLaw(0)
Rx Gain = 0dB
Tx Gain = 0dB
Guard Time = 0mS
DAA Start Up = Enabled
And another area is the following, only for the overall voice from and to VOIP.
Receive Gain (PCM -> IP) = -2 dB
Transmit Gain (IP -> PCM) = -4 dB
Try with the first set of settings first