We’re using Polycom SPIP 321 phones, and one extension in particular keeps receiving phantom calls from “a1000”.
By phantom calls, I mean that the phone rings and the call shows up in the phone’s history, but it is not saved on the PBX’s CDR anywhere and I don’t see them when I have an “asterisk -vvvvvvvvvvr” console open.
These calls are happening at random intervals, nobody is on the other end of the call if we answer it, and that’s about all I’ve got.
FPBX 12.0.13
Asterisk 11.13
CentOS 6.5
If your phones are exposed to the interwebs (port 5060) in any way then the calls might have nothing to do with your Asterisk, check your port forwarding on the router(s) in front of them.
Thanks, Dick[o] 
It’s a remote office but probably; do you know of any way to reject unregistered calls on these guys? I’ll do some testing over here as well…
Just don’t use 5060 
Heh…we’ve seen some spam on ALL ports on our servers, but I’ll suggest that to the site admin 
You have 64k ports to choose from, use “connection tracking” on your firewall to detect and drop the knuckle-draggers before they can do damage.
I’m not willing to admit the level of security this site has 
I’ve got the rest of the company locked down, but this one location (our home office across the country) won’t spend the money on even a sonicwall
Then tell them to stop whining 
(You should never need to forward 5060 on the client side firewall, if you don’t you wont get that . . . )
I agree with Dicko.
Also, the Edgeroute lite is $100.00 and I’d argue way better than SonicWall.
How cheap do they want it? I’ve seen a few thrifty admins getting some sonicwall’s at the local recycle for about $50 a piece. According to the person I was talking with there, the ones they were buying there were still supported. Even at that though, the mindset that security costs too much money only lasts until somebody is frantically trying to find the backups. Good luck to your home office.
Eric