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Many calls from unknown numbers

Got the Grandstream ATA operational yesterday

During the night and up to now (07h45) the phone has rung with Unknown Number several times and there is no-one there, just dialing tone

Any suggestions please?

The number is 27879432459


We took the TP-Link router back and got another one that cost R1200

There is no difference.  Within 30 mins, the phones ring non-stop.  The ATA device shows "ring" all the time.  Outgoing calls are impossible

Is it the line?

Is it the ATA adaptor?

Is it the handsets?

You tell me to NAT the network.  How does one NAT the network?  There is no reference to this in the router's manual

Hi Chris

Best would be to contact the makers of the router and ask them how to secure your network with their router. Network Address Translation(NAT) needs to take place for the network to be secure. I am positive that they will know exactly how to do this on the router that they make

These phantom calls are also known as SIPvicious are a type of SIP denial of service attack. This happens when your phone sits on your live IP address. A bot which is doing port scans on random public IP addresses will find an open port. The bot will then send SIP signals to this device on a general SIP port and the phone will ring. Calls usually come from 100 or 101 etc. You will not find any record of these calls in the CDR's on your PBX as it is just a signal sent to the IP and it is not an actual call

Ways to fix this:
- Have a look at your NAT rules on your router, make sure it is masquerading your internal IP's so they are not accessible from outside of your network.- Up the firewall level on your router- Deploy a ViBE router (This is essentially a VPN and can't have packets injected)- Try change the port on your phone, try something higher like 5090. They only scan the really common ports such as 5060, 5061, 5062 etc)
Please let me know if you require any further information. Have a great day!

Serge Jeannet has a Grandstream ATA device

Is this where the ports are configured?

Or is it somewhere else?


Hi Chris

It will be called something like local SIP port. The best way is just to ensure that the router has NATting enabled, then it will be secure and no unauthorized connections will be able to get to the phone

Thanks!  I'll look tomorrow

I am at Serge Jeannet's house

The moment I plug in a POTS phone to the ATA, it starts ringing.  It rings for 10 seconds, there is a pause for 3-4 seconds and it rings again

The router is a TP-Link TL-WR840N

What values are inserted into this space please?


The configuration page of the Grandstream shows "Ring" all the time


I really do not know how to solve this and would really appreciate your assistance


Can you please let me know how to resolve the above problem?

Mr Jeannet calls me every day asking about it

Hi Chris

The router is not securing the network. If the router does not have the ability to NAT the network, then another router needs to be installed.

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