[HOW TO] Cisco SX20 : receiving incoming calls from unknown sources

Hi,

We are using a Cisco SX20, this is working fine. But, the only problem is the fact there are a lot of unknown established calls.

I told service provider, and they said me: the attacker scans port SIP on the internet to attack internal LAN.

Hummmm,

Googled, I known, my device is being probed by a SIP Scanner such as SIP Vicious.

4 days ago, I try to OFF DoNotDisturb Mode in SX20 Web Configuration. But it stills problem.

And then, yesterday I turned OFF ListenPort on SIP tab in SX20 Web Configuration.

Nice! from now on I don't receive unknown established call.
Thank you for reading this article, please a comment if you are interested.

Tiến Phan - R0039

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