I am looking for suggestions. I have a toll free number. I received many incoming calls from all over the country. Most of them are not real customers. I get a very expensive bills every month because of these spam calls. The number is in voip.ms and I set the route to “hang up” so people cannot keep making calls to this toll free number for about half year. Recently I enable it and route it to my PBX and I start getting spam calls again. I feel like I can’t use this number anymore because the cost is high.
I find one thing is weird. The number is forwarded to voicemail directly and the message lasts only 1 second. That means the phone call takes 1 or 2 seconds. But voip.ms billing system show the call last more than 1 minutes. Sometimes the CDR in my system doesn’t show the calls at all, sometimes voipms CDR shows the time match to my pbx system.
Here is a sample:
2021-06-18 18:05:11 4192221752 844xxxxx35 Inbound DID 01:29 0.0190 0.0285
this is the CDR in voip.ms billing system. It shows the call last 1:29. But I don’t see it in my CDR of my PBX. But I received 1 second voicemail from the PBX. And I also have a call record in the Asterisk.
The 1 second spam call voicemail message is always silent. And my voicemail message maximum time is 180 seconds. And the time in voip.ms CDR is usually 1min29 which is almost the same to the 180 seconds limit.
For me using my cellphone to call my toll free number, I can see the calling time of both CDR (voip.ms billing system and my PBX) can match, the voicemail time also match. Everything seems perfectly fine.
I am using filter feature provided by voip.ms now. I allow only local area numbers to call. If people using some other area code to call, they will be hung up. This is not working for us.
So my question is how they call me without my PBX counting the time? And what is happening during the call? Is there any other ways to prevent this thing happening? I don’t think I am the only victim.
Let me know if you need call logs. Thank you very much.