Call Progress tones for india
Below is the configurtion used in the grandstream gateways to detect the busytone
# Dial Tone : ch1-8:f1=400@-10,f2=0@-10,c=0/0;
# Ringback Tone : ch1-8:f1=400@-10,f2=0@-10,c=40/20-40/200;
# Busy Tone : ch1-8:f1=400@-10,f2=0@-10,c=75/75;
# Reorder Tone : ch1-8:f1=400@-10,f2=0@-10,c=25/25;
# Confirmation Tone : ch1-8:f1=400@-10,f2=0@-10,c=100/400;
AC termination Impedence for india
270 Ohm + (750 Ohm || 150 nF) -- Most of Europe
220 Ohm + (820 Ohm || 120 nF) – Australia, New Zealand
220 Ohm + (820 Ohm || 115 nF) – Austria, Bulgaria, Germany, Slovakia, South Africa
370 Ohm + (620 Ohm || 310 nF) – UK., India
for other coutries downloadlink
refer link: https://sites.google.com/a/3cx.com/3cx-wiki/documentation/gateways/how-do-i-configure-tonesets-for-my-country-on-a-grandstream-gxw-4108