I met problem when FXO port on cisco router can`t get disconnect messages ,because of it cisco ip phone remains ringing.
When dialing from ip phone ,it begins to call after 15-20 seconds.
I have the following topology:
PSTN gives phone connection through SIP to Grandstream and from grandstream by FXO to Router.
I tried to make cusctom cptone,but it didn`t help me.
There is my voice port configuration :
voice-port 0/0/0
ring number 2
groundstart auto-tip delay 1
echo-cancel coverage 64
no vad
timing hookflash-out 50
timing guard-out 3000
caller-id enable
voice-port 0/0/1
ring number 2
no battery-reversal
groundstart auto-tip delay 1
signal groundStart
timing hookflash-out 50
timing guard-out 3000
caller-id enable
Also i try to discover from Telco which cptone ,frequency,cadence, grandsteam h 502 use ,and got answer that Telco engineers don`t know ,they staied it by default.In grandstream datasheets i also couldn`t find any usefull information
