Unknown call on call monitor

Hello, i am new in asterisk and freepbx. there are some calls, i do not understand and i don’t make on call monitor. can someone tell me what is that calls? thank you

Date Time Caller ID Source Destination Duration Monitor
2013-04-18 21:41:14 “6001” <6001> 6001 s 0 sec
2013-04-18 21:41:11 “6001” <6001> 6001 s 0 sec
2013-04-18 21:41:07 “6001” <6001> 6001 s 1 sec
2013-04-18 21:11:24 “1000” <1000> 1000 s 0 sec
2013-04-18 21:11:23 “1000” <1000> 1000 s 0 sec
2013-04-18 21:11:22 “1000” <1000> 1000 s 1 sec
2013-04-18 21:11:21 “1000” <1000> 1000 s 1 sec
2013-04-18 19:55:16 “2005” <2005> 2005 s 0 sec
2013-04-18 19:55:14 “2005” <2005> 2005 s 0 sec
2013-04-18 19:55:13 “2005” <2005> 2005 s 0 sec
2013-04-18 19:55:12 “2005” <2005> 2005 s 1 sec
2013-04-18 19:33:23 “1001” <1001> 1001 s 1 sec
2013-04-18 19:33:19 “1001” <1001> 1001 s 0 sec
2013-04-18 19:33:16 “1001” <1001> 1001 s 1 sec

Looks like typical background scanner activity looking for vulnerabilities.

set allowguests=no in sip config which just disables the logging of this activity. Some SIP trunks don’t work properly with this setting but most do.

As long as you use good passwords and don’t have allowanonymous=yes you don’t have to worry much about this activity.