Hello,  I have set up two extensions in my network, both have identical configurations. When I call from ext A to ext B I have no problem; ext B rings and I can hear audio. Now when I call from ext B to ext A I get the following error: "Got SIP response 400 "Bad From URI" back from 172.10.30.15". Could someone let me know why this happens, what could be the issue and what I need to check for? Thank you for your help.   Arun Jayaprakash