[Freeswitch-users] How to make the heard DTMF tone more longer

Dear all: I try to send DTMF tone. I use two method in lua 1.queue_dtm after bridge 2. send_dtmf in a session these two methods are working and call my phone successfully But, I got a problem is... After bridge, I hear soon DTMF tones. The heard DTMF tones are so short. It is very strange to feel as broken. Even though I set and increase the tone_duration as below: queue_dtmf "12345678@5000" or send_dtmf "12345678@5000" The heard DTMF tones also very short, but the duration between inter-digit become longer... Somebody tell me how to make "heard DTMF tone" longer...or silent the dial tone and sent DTMF tones. Thanks a lot for your support. Best regards, Joy