I have pstn (isdn) gateway 192.168.0.163, and I make calls using prefix "8" Here's a log from a local call (using CiscoATA186 and Wu-chuang Sipphone):

Apr 7 20:49:09 domenet /usr/sbin/ser[18289]: ACC: transaction answered: method=PRACK, i-uri=sip:457@192.168.0.145:5060, o-uri=sip:457@192.168.0.145:5060;user=phone;transport=udp, call_id=jFB1bc1nyfwVovpk@192.168.0.134, from="493" sip:493@192.168.0.122;tag=ncHI214LorUb7iWW, code=200 . Apr 7 20:49:11 domenet /usr/sbin/ser[18283]: ACC: transaction answered: method=INVITE, i-uri=sip:457@192.168.0.122, o-uri=sip:457@192.168.0.145:5060;user=phone;transport=udp, call_id=jFB1bc1nyfwVovpk@192.168.0.134, from="493" sip:493@192.168.0.122;tag=ncHI214LorUb7iWW, code=200 Apr 7 20:49:11 domenet /usr/sbin/ser[18285]: ACC: request acknowledged: method=ACK, i-uri=sip:457@192.168.0.145:5060, o-uri=sip:457@192.168.0.145:5060;user=phone;transport=udp, call_id=jFB1bc1nyfwVovpk@192.168.0.134, from="493" sip:493@192.168.0.122;tag=ncHI214LorUb7iWW, code=200

And here's a log from calling to pstn (using Wu-chuang sipphone and pstn gateway) to number 0506633351 (isdn:506633351) :

Apr 7 20:52:54 domenet /usr/sbin/ser[18284]: ACC: request acknowledged: method=ACK, i-uri=sip:8506633351@192.168.0.163:5060, o-uri=sip:8506633351@192.168.0.163:5060, call_id=yPeLkYYVQnG8fiOm@192.168.0.134, from="493" sip:493@192.168.0.122;tag=QpR2G8JxdXTiq265, code=200

As You can see, there's no BYE message ,but only if the pstn-side disconnects. If the LAN side disconnects, theres a succesfull BYE message.

I use forwarding to pstn using the loop:

if (loose_route()) { t_relay(); break; }

if (method=="INVITE") { record_route(); }; setflag(1); if (uri=~"^sip:8[0-9]{3}@*") { log(1, "Forwarding to ISDN..."); rewritehostport ("192.168.0.163:5060"); t_relay(); log(1, "..forwarded\n"); break; };

Moreover, calling PSTN there's only silence in LAN's side, although PSTN hear LAN very good.

Where am i wrong ?