Calls from Unknown number

[AbdulKader Anwar]

Hi,

we have issue with our pabx started recently, receiving calls from unknown numbers and if we answer there is no voice and after that we have issue with outgoing calls, cannot hear voice. But the same time if someone calls to the extension can hear. And after sometimes the outgoing callls are working fine. It is happening on not any specific time or day but it is random. All the outgoing calls got restored automatically and that also not in any specific time but sometimes within 5 - 10 mins and sometimes it takes hours

Is this any kind of attack. Everytime i am adding the number to Blacklist number and after sometimes i am getting the same calls from another number.

Getting calls from the number 88908xxxxxx. the last five number changing everytime.

Any one facing these kind of issue or any fix for this. I am really tired of getting complaints that outgoing calls are not working

Very much appreciated your swift response.

Or is there anyway we can track where these call originating from.

thanks
anwar

 

[leejor]

Since you don't specify in which country this is happening in, it is hard to guess where the calls might originate even when you list the number. You may want to speak with your provider to see if they can help trace, and, or block the calls, especially if they happen on a regular basis.

 

[AbdulKader Anwar]

Since you don't specify in which country this is happening in, it is hard to guess where the calls might originate even when you list the number. You may want to speak with your provider to see if they can help trace, and, or block the calls, especially if they happen on a regular basis.

ok sorry i am from maldives and our idd code is +960. requested service provider with the call logs and they are saying they didnt see any call history during that time

 

[cobaltit]

So I think you might be dealing with two different issues. For the ghost calls if you are receiving calls on your phones without a corresponding 3CX cal log entry then chances are these are ghost calls going directly to the phones. This should be resolved with the current phone firmware/templates for supported phones. For the outbound call audio issue you might need to increase your RTP port ranges. Does the firewall checker pass?

 

[AbdulKader Anwar]

So I think you might be dealing with two different issues. For the ghost calls if you are receiving calls on your phones without a corresponding 3CX cal log entry then chances are these are ghost calls going directly to the phones. This should be resolved with the current phone firmware/templates for supported phones. For the outbound call audio issue you might need to increase your RTP port ranges. Does the firewall checker pass?

Hi @cobaltit,

thanks for your reply. we managed to fix i hope, so far we are stable. we blocked all the internet connections and allow outbound traffic to 3cx recommended sites only. We are suspecting kind of attacks happening as we published our 3cx server and same has been removed now. So far it is stable.

Please refer the below thread, we are having the same similiar infra design.

https://www.3cx.com/community/threads/external-calls-problem.62591/

thanks
anwar

 

[YiannisH_3CX]

I would recommend keeping an eye on the issue and see if it happens again. Obviously if you lock down the firewall the firewall checker will fail but if you are still having issues with outbound calls then you will need to pass the firewall checker to verify that all ports are ok. Also as mentioned make sure that your phones are running the latest supported firmware and default templates.