I keep getting calls that when I pick up- are not there. weird calls- appearing from an extension or an 888 I have never heard of. How do I block these calls? whenever I pick up no one answers- they have been going all day- driving me crazy.
a simple question, did you firewall the correct NAT and ACL?
Damiano is correct.
The calls are likely not coming into your PBX, but directly to the phone. The phone rings, displays an odd number or name, you pick up and no one is there. There are sometimes referred to as ghost calls.
You need to get you IT folks to close down the firewall such that only desired IPs are allowed in. They can also possibly enable some settings within the phone such that the phone(s) will only accept messages from the PBX and not others.
Do a forum search for ghost calls, while getting IT involved.