Keep receiving calls from numbers like 100, 1000, 1002, etc.

[Anonymous]

Hi,

Sorry if this has already been said.

I am new to VoIP. I have a polycom VVX101 phone and Sipgate Basic. I moved because my ISP raised their call rates. A friend who works in an office gave me their old polycom VVX 101. It has been working perfectly until I started to get these calls. I did some googling and saw they were called spit calls.

How do I stop them? It's annoying being called at 12am!

Thanks,
Jim

[SteffenBaierUK · Accepted solution]

Hello Jim,

welcome to the Polycom Community.

The community's VoIP FAQ contains this post here:

Oct 24 2014 Question:How can I prevent tools like sipvicious or nuisance Cisco calls ringing my phone?

Resolution: Please check => here <= or Security Center: Security Bulletin Relating to Worldwide Botnet Dialing H.323-Capable Systems

Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.

Best Regards

Steffen Baier

Polycom Global Services

[Anonymous]

The best method to resolve this is to fix the insecure configuration of your WAN router.

It implements something called "full cone NAT", which means it is basically a port forward, and as a result of this, the sip scanners are able to contact your phone, causing it to ring randomly.

You want to be using restricted or port restricted NAT. There are more details here: https://www.think-like-a-computer.com/2011/09/16/types-of-nat/

If you are unable to resolve this, ie because you are using a junk router provided by your ISP which does not provide access to modify this, then enabling INVITE vaidation is the next best resolution. The illgtimate packets will still be routed to your phone by your router's insecure configuration, but the phone will reject them as they did not originate from your legitimate SIP server.

The 3rd option is to change the local listen port, so that the phone is not listening on port 5060 (or 5080) which is where most of these scanners try looking for vulnerable systems.

In the production environment of the telephony provider I work for, we use a combination of INVITE validation, and changing the listen port away from 5060 to avoid these issues.