Hi Freeswitchers: I have been trying to detect *India* ringback tone using spandsp.conf.xml My understanding is that* f1* and *f2* are the Frequency and *min* and *max* is the Tone duration value. For example: *Based on ITU-T reference India progress tones are:* ring = 400*25/400,0/200,400*25/400,0/2000 *Questions* a) How to show the Tone frequency received? b) What is the meaning for the values assigned to f1 and f2 in debug mode. I see possible values: - -1 - 1 - 2 c) Is there an option to configure modulation for Tone frequency as specified in ITU standard (*25 above)? d) Sample configuration will be appreciated. *Configuration* <tone name="RING_TONE"> <element freq1="400" freq2="0" min="384" max="400"/> <element freq1="0" freq2="0" min="200" max="224"/> <element freq1="400" freq2="0" min="384" max="400"/> <element freq1="0" freq2="0" min="1968" max="1984"/> </tone> When debugging: I have enabled already debug level to 2. 2017-02-13 02:59:32.080389 [DEBUG] mod_spandsp_dsp.c:705 Tone segment:* f1 = 1, f2 = 2, duration = 400* 2017-02-13 02:59:32.300524 [DEBUG] mod_spandsp_dsp.c:705 Tone segment:* f1 = -1, f2 = -1, duration = 224* 2017-02-13 02:59:32.680369 [DEBUG] mod_spandsp_dsp.c:705 Tone segment:* f1 = 1, f2 = 2, duration = 384* 2017-02-13 02:59:34.680384 [DEBUG] mod_spandsp_dsp.c:705 Tone segment:* f1 = -1, f2 = -1, duration = 1984* http://pastebin.com/xm8xN9R3 Thanks -Gonzalo