Problem seems to start from here


[2013-04-15 11:31:05] WARNING[27293] chan_sip.c: sip_xmit of 0x7f6b9c026bd0 (len 584) to 1.1.140.168:5071 returned -2: Success
[2013-04-15 11:31:05] WARNING[27293] chan_sip.c: sip_xmit of 0x7f6b9c01adb0 (len 606) to 1.1.140.168:5071 returned -2: Success
[2013-04-15 11:31:05] WARNING[27293] chan_sip.c: sip_xmit of 0x7f6b9c018800 (len 883) to 1.1.140.168:5071 returned -2: Success
[2013-04-15 11:31:05] WARNING[27293] chan_sip.c: sip_xmit of 0x7f6b9c029c80 (len 897) to 1.1.140.168:5071 returned -2: Success

then few seconds later peer becomes unreachable

[2013-04-15 11:31:09] NOTICE[16636] chan_sip.c: Peer '1217' is now UNREACHABLE!  Last qualify: 249

and then 

[2013-04-15 11:31:11] WARNING[16636] chan_sip.c: SIP transfer to cid:74acc5e3 with response (420).
[2013-04-15 11:31:19] WARNING[16636] chan_sip.c: sip_xmit of 0x7f6ba007e040 (len 584) to 1.1.140.168:5071 returned -2: Interrupted system call

After this message below asterisk was restarted


[2013-04-15 14:05:39] ERROR[10734] tcptls.c: Unable to connect SIP socket to 1.1.140.168:5071: Connection refused
[2013-04-15 14:05:43] NOTICE[16636] chan_sip.c: Peer '1217' is now UNREACHABLE!  Last qualify: 0
[2013-04-15 14:05:53] ERROR[10744] tcptls.c: Unable to connect SIP socket to 1.1.140.168:5071: Connection refused
[2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Parsing '/etc/asterisk/asterisk.conf': [2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Found
[2013-04-15 14:06:15] VERBOSE[10788] manager.c:   == Manager registered action DataGet
[2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Parsing '/etc/asterisk/codecs.conf': [2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Found
[2013-04-15 14:06:15] VERBOSE[10788] loader.c:  Asterisk Dynamic Loader Starting:
[2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Parsing '/etc/asterisk/modules.conf': [2013-04-15 14:06:15] VERBOSE[10788] config.c:   == Found
[2013-04-15 14:06:15] NOTICE[10788] loader.c: 2 modules will be loaded.

This happpens with some other extensions as well, the phone I am using is cisco SPA504G