It’s been a while since my last update. Having another kid definitely limits the time to create a post, however she is sleeping right now. I’m sitting here with a Red Bull in one hand and a Secure CRT window open and ready to go.
Occasionally in the carrier world, your network might be blasted with a large number of calls from a dialer. While certain devices on the network might be able to handle the calls per second increase, others could experience an issue due to licensing. For instance, if you are running a BroadWorks Network Server and you are licensed for “X” transactions per second and this dialer puts you over the limit , you will start rejecting calls from valid subscribers.
Using the Acme Packet Net-Net series you have a few options for blocking these call attempts. One way is to route the calls to a fake realm / session agent and reject it from there. The issue with this method is that a SIP 503 is sent back up stream. If you have requested your upstream carrier to route advance upon receiving a 503, you’ve succeeded in migrating these call attempts to a different trunk on your network. This is most likely not what you are looking for. Instead you will need to have the SBC translate the 503 to a different response code.
Lets start with the mechanics of the response map. This actually very straight forward. you first supply a name for the response-map. Next you enter the transmitted code (recv-code : 503) and what you want it translated to (xmit-code : 404). You can also add a custom reason to the response code.
reason "User not Found"
From here, you need a few more items in place (a realm, local-policy, an interface and a session-agent)
Next, you need a sip-interface:
…a Session Agent (notice the ‘local-response-code’ value is populated. This is where you enter the name of the response map that you have created)
description "SA to apply response-map"
…A local-policy for routing of course :
description "Policy to send harassing calls to a fake SA"
Add these config sections, perform a save / activate and you should be set.