If you are using a sip phone, you are MUCH better off using non audio based dtmf like rfc-2833.  If you are already using this, its possible that what is happening is the phone is sending the dtmf as audio and 2833, at which point, you should not have to use spandsp_start_dtmf at all.  If the phone is sending only audio, and is not capable of using any other method, you will need to pull a pcap of this call, use wireshark to extract the audio, and do some analysis of the audio to figure out why it is detecting multiple digits.

On Jan 19, 2015, at 4:38 AM, Nagalenoj H. <nagalenoj@gmail.com> wrote:

Hi,

When I use spandsp_start_dtmf along with play_and_get_digits, '#' is getting detected many times, though it is pressed once.

Other DTMFs are getting detected properly, whereas the '#' is getting detected 2 or 3 times.

I have checked the SIP phone's settings, I do not find anything wrong there.

What could be the reason? Is this because of some SIP phone setting? Here is the freeswitch log,

2015-01-19 09:33:39.671681 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [1]
2015-01-19 09:33:39.671681 [DEBUG] switch_channel.c:488 RECV DTMF 1:2000
2015-01-19 09:33:39.851686 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [1], duration = 191 ms
2015-01-19 09:33:40.071688 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [4]
2015-01-19 09:33:40.071688 [DEBUG] switch_channel.c:488 RECV DTMF 4:2000
2015-01-19 09:33:40.251687 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [4], duration = 153 ms
2015-01-19 09:33:40.431699 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [7]
2015-01-19 09:33:40.431699 [DEBUG] switch_channel.c:488 RECV DTMF 7:2000
2015-01-19 09:33:40.631680 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [7], duration = 204 ms
2015-01-19 09:33:40.851688 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [4]
2015-01-19 09:33:40.851688 [DEBUG] switch_channel.c:488 RECV DTMF 4:2000
2015-01-19 09:33:40.971695 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [4], duration = 127 ms
2015-01-19 09:33:41.151691 [DEBUG] switch_core_session.c:1053 Send signal sofia/internal/sip:278@192.168.2.86:5060 [BREAK]
2015-01-19 09:33:41.171701 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [7]
2015-01-19 09:33:41.171701 [DEBUG] switch_channel.c:488 RECV DTMF 7:2000
2015-01-19 09:33:41.351680 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [7], duration = 191 ms
2015-01-19 09:33:41.371686 [DEBUG] switch_ivr_play_say.c:1314 Codec Activated L16@8000hz 1 channels 20ms
2015-01-19 09:33:41.691686 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [#]
2015-01-19 09:33:41.691686 [DEBUG] switch_channel.c:488 RECV DTMF #:2000
EXECUTE sofia/internal/392@3427.vbiz.mundio.com flush_dtmf()
2015-01-19 09:33:41.691686 [DEBUG] switch_ivr_play_say.c:1314 Codec Activated L16@8000hz 1 channels 30ms
2015-01-19 09:33:41.711684 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [#], duration = 38 ms
2015-01-19 09:33:41.771683 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [#]
2015-01-19 09:33:41.771683 [DEBUG] switch_channel.c:488 RECV DTMF #:2000
2015-01-19 09:33:41.771683 [DEBUG] switch_ivr_play_say.c:1747 done playing file file_string:///root/united_fone/voice_files/en//CR_enter_conf_pin.wav
2015-01-19 09:33:41.771683 [DEBUG] switch_ivr_play_say.c:1314 Codec Activated L16@8000hz 1 channels 30ms
2015-01-19 09:33:41.811686 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [#], duration = 25 ms
2015-01-19 09:33:41.871691 [DEBUG] mod_spandsp_dsp.c:373 DTMF BEGIN DETECTED: [#]
2015-01-19 09:33:41.871691 [DEBUG] switch_channel.c:488 RECV DTMF #:2000
2015-01-19 09:33:41.951681 [DEBUG] mod_spandsp_dsp.c:385 DTMF END DETECTED: [#], duration = 76 ms

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