From address missing 'sip:', using it anyway

Hello,
I see the following error in the logs

[2013-02-06 14:11:31] NOTICE[1531]: chan_sip.c:16586 check_user_full: From address missing ‘sip:’, using it anyway
== Using SIP RTP TOS bits 184
== Using SIP RTP CoS mark 5
[2013-02-06 14:11:31] WARNING[1531]: chan_sip.c:15789 get_destination: Not a SIP header ()?

Does anybody know how to stop this error? It does not seem to be affecting
performance on the Asterisk 1.8.19.0 running on CentOS release 6.2. I have
google it but empty!

Thanks,
Khatnaa