I'm using Kamailio 3.1.5 in front of asterisk servers. Kamailio handles all the SIP registrations. Calls from SIP phones are forwarded to asterisks and then dialled out to Kamailio.

root@SBCserver:~# kamailio -V

version: kamailio 3.1.5 (x86_64/linux) 76fff5

flags: STATS: Off, USE_IPV6, USE_TCP, USE_TLS, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, DBG_QM_MALLOC, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES

ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535, PKG_SIZE 4MB

poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.

id: 76fff5

compiled on 08:21:33 Oct 27 2011 with gcc 4.6.1

root@SBCserver:~#

When call is initiated from a softphone and is in ringing phase, CANCEL just don't work. I've done some initial debugging and the following piece of code in main route is failing.

# CANCEL processing

if (is_method("CANCEL"))

{

xlog("L_NOTICE","$rm from $fu (IP:$si:$sp) ---CAPTURED IN MAIN---\n");

if (t_check_trans()){

t_relay();

xlog("L_NOTICE","$rm from $fu (IP:$si:$sp) ---CHECK TRANS TRUE---\n");

}

xlog("L_NOTICE","$rm from $fu (IP:$si:$sp) ---CHECK TRANS FALSE---\n");

exit;

}