Toll free number receive many spam calls


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 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 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 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 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 ( billing system and my PBX) can match, the voicemail time also match. Everything seems perfectly fine.
I am using filter feature provided by 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.


Have you contacted about this problem?

(Simon Telephonics) #3

@Vietyank you want telemarketers, you should buy @aaaa2209 spammy phone number.


They said they will check why I was billed. I am waiting for their response. I still want to ask here because it seems to me won’t help. They will probably tell me it did occurred that long.
Also the problem wasn’t related. This number was originally bought from It worked fine for at least 4 years. I got hundreds dollars bill every month since last year and then I ported out to I thought it was issue. But I don’t think so now.
I did some google check. It’s some ISP do this because they can make money from it. I don’t quite understand the theory but I think it’s possible. Here is an article about it.


Hello Billsimon. Sorry I don’t quite understand. What do you mean “buy spammy phone number”? I used the toll free number for a few years without problem. It was working fine at the beginning. Do you mean I should buy some service to keep the telemarketers away? And the service is called “spammy phone number”? Thanks

(Simon Telephonics) #6

Sorry to confuse you. @Vietyank started a different topic on the forum where he said he wanted to receive telemarketer calls. I am sure some of your “spam calls” are telemarketers. I was suggesting that he might like to have your phone number so that he can receive those calls.


Find the Asterisk log for one of these calls. Today’s log is /var/log/asterisk/full , though you will (by default) see a week’s worth of logs with names like full-20210622 . Paste the log for a complete call at and post the link here.


Hello @Stewart1 sorry for the late reply. I was busy during the week.
Please see the call logs here. I didn’t post the whole day’s log. It’s only two calls. The first call log is from the spam number 4192221752. The second call log is from my phone number 2127209845. My toll free number is 8447446946. The numbers are modified for privacy concern.

Also the support reply me:
The logs for this call were sent to your subaccount and were answered by your device, either because the phone handset was lifted or because it hit a ‘channel’ in your device, either a voicemail or a recording. You might need to check why they are reaching a channel since if your incoming calls do this, they will be counted as answered.

Thanks again.


Is this even a FreePBX system? I don’t recognize any of the dial plan subroutines. Did you write your own dial plan to replace essentially everything, or is this a competing GUI-for-Asterisk product?

But in any case, the call was routed to voicemail, after routing to extension 901 which was apparently offline. The “caller” was silent, so after playing the greeting and instructions and detecting 10 seconds of silence, Asterisk played instructions to the caller, repeating them three times before hanging up. The result was that the call was connected for 1:29.

I can think of three ways to mitigate this problem; you might implement two or all three:

  1. Hang up calls that you are reasonably certain are malicious, e.g. based on caller ID, without answering. If you believe that this call should have been so handled, please explain.

  2. Reduce the duration of the remaining malicious calls. For example, before sending an unanswered call to voicemail, route to an IVR “To leave a message for George, please press 7”. If the key is not pressed within five seconds, hang up.

  3. Port the number to a lower cost service. For example, BulkVS is $0.0055/min. vs $0.019 for (both are 6 second billing). Unfortunately, there is a $0.002 per call surcharge for a mandatory CNAM lookup, so calls of less than 6 seconds would actually cost more. I believe that the IVR scheme could reasonably be set to hang up in less than 12 seconds; BulkVS would cost $.0031 vs. @ $0.0038 vs. your present cost $0.0285 for the 1:29 call.


Hello @Stewart1. The PBX is called VitalPBX. It’s not FreePBX system. I don’t know how to write any dial plan and I didn’t make any change of it.
Sorry I didn’t make it clear at first.

I think I can repeat the spam call situation now. I called the toll free number with my cell phone, I mute my call and after 10 second silence the vm will activate saying “press 1 to listen , press 2 to rerecord…” about four times before hanging up.
And I only receive a 1 second voicemail even I got a 1:30 bill.
The vm will stop recording after 10 second silence. I didn’t know that. I always make sound when I test recording the voicemail. So I always get a more than one second long voicemail recording.

About your three ways to mitigate the issue:
1, We prefer to use IVR to divert calls. This one doesn’t work very well.
2, I think pressing 7 to screen robot is a very good idea. I can put it before an IVR to block them.
3, Thank you for the suggestion of BulkVS. I will definitely take a look. Is the quality ok comparing to I am satisfied with sound quality but I am very interested in to know more reasonable phone cost from different ISP. Also do you have any good CNAM lookup provider suggestions? I paid about $100-$200 CNAM lookup fee for very month. I just found out that BulkVS charge $0.002 which is one fourth of I hope they provide similar quality. I will give it a try.

Thank you so much for your suggestions. They are very helpful. I really appreciate it.

(David55) #11

In that case you should be using

People here know about how the FreePBX dialplan and tools behave, but not how VitaPBX works, and people on the Asterisk forum will assume you can write dialplans and understand how your current one works.


Thank you for letting me know. @david55

@Stewart1 I checked online and the BulkVS has very good reviews. Thanks again.

(Jared Busch) #13

It was definitely VitalPBX, because of this: /ombutel-voicemail/

VitalPBX used to be Ombutel, which was a partnership of Xorcom and Telesoft.
The two companies split and anf forked the project into their own things.
Telesoft made VitalPBX and Xorcom made Xorcom Complete PBX.
Also VitalPBX is completely closed source. They let you hook into dial plan in one place to get custom dial plan injected, but that’s it.

(Dave Burgess) #14

Sounds to me like the OP needs to switch more than his provider.

(system) closed #15

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