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for voice calls, the best thing I ever did was set up my own asterisk system with a DID that answers as an IVR saying something like "you have reached $NAME, th

for voice calls, the best thing I ever did was set up my own asterisk system with a DID that answers as an IVR saying something like "you have reached $NAME, this is an anti-spam system, please confirm you are a human by entering the digits five three zero nine to be connected". If people then put in the DTMF tones for 5309, or whatever code it might be this month, it initiates an outbound call to my actual cellphone and bridges the calls together. In many cases I don't give out my direct cellphone number to 3rd parties, or anyone who isn't a close family member or colleague, I only give out the DID of the system with the filtering IVR on it. I do still receive the occasional coldcall spam on my cellphone's direct number, which isn't entirely avoidable, but those are only random calls which aren't looking for me in particular. By only giving out the phone number of the filtering DID, I avoid my number being entered into many random third parties' CRM systems which are inevitably subject to data leaks, copying, data sharing with other 3rd parties, sales and marketing campaigns, etc.

gruez 5y ago
Does this system pass through the original caller's info on caller id?
- walrus01 5y ago
  yes, it preserves caller ID on the outbound call initiated on the SIP trunk, my wholesale voip provider allows me to pass CID on outbound calls.
h0l0cube 5y ago
Seems like something people would pay for.
- walrus01 5y ago
  I have been thinking about turning it into a small project people can pay for, would first want to set up a series of scripts that could auto-provision everything immediately upon payment. Right now it's all manual since I'm the only person with the equivalent of admin/root on the asterisk system, and I've customized it for only my needs and those of my spouse.
  - h0l0cube 5y ago
    It certainly doesn't sound like a trivial project, but given the preponderance of spam calls these days it seems like perfect timing for a product like this.
  - Scoundreller 5y ago
    Should be able to do it all through VoIP.ms subaccounts. Complexity would be having to port in phone numbers (around here, that auto cancels your cellular account!), but see my other post, people could forward all calls to the server and proven humans would ring a soft phone.
gnicholas 5y ago
Can you provide more details about how you set this up? Does it provide a similar benefit to using Google Voice with call screening enabled? If my phone number is already out in the wild (apparently), is there anything I can do at this point? Or is the only solution to get a new phone number, never give it to strangers, and only give out a virtual number with screening?
- walrus01 5y ago
  It's related to what I do for work so what I've done I would not recommend to everyone... It's a FreePBX/Asterisk VM (CentOS 64-bit) that runs on a system in colocation somewhere at a major traffic exchange point. It is one of a number of VMs that run my personal infrastructure. It has a SIP trunk to a wholesale voip provider, where several DIDs reside. The incoming calls to the DIDs first hit my SIP trunking provider, which sends the incoming call signals to my voip server, which processes the call flow by starting with the IVR announcement I previously described. It is generally the same idea as google voice with call screening but I have approached it from a DIY perspective where I want to have full admin access over everything, except at the SS7/PSTN level where the DIDs are at my SIP trunking provider. Everything related to the incoming and outgoing calls I can customize for other unique purposes.
  - gnicholas 5y ago
    Thanks! The more I read HN, the less I realize I know!
- Scoundreller 5y ago
  One way to do this without setting up a server or moving your phone number to another provider: 1. setup an unconditional redirect for all calls on your cell phone to a voip.ms DID that you set up ($1/month). This redirect functionality is baked into the gsm system: https://www.geckobeach.com/cellular/secrets/gsmcodes.php https://www.geckobeach.com/cellular/secrets/gsmcodes.php 2. On voip.ms, setup an IVR with a recorded message. Set it up to connect extension “1-2-3-4” or whatever your code is to your softphone. You should be able to whitelist numbers to auto-forward to your soft phone. Cool thing is you can setup voicemail through this so you receive them as email attachments. SMS still works through your cell phone. Outgoing calls still go through your cellphone.
mindslight 5y ago
I do greylisting. The first call from an unknown number plays asterisk standard recordings - SIT + "please try again". A successive call from the same number rings through. Legitimate callers have had no problem. I set it up this way because it was originally operating on a landline "in parallel" so that if the server failed the phones would still work. Next up is some kind of system that takes calls from places that you can never reach directly and instead call you back at bleeding-eyes-o'clock (eg doctors' offices), answers the call, and puts the caller on hold while I wake up. "Bucket of stomach fluid" can be a two way street.
- bityard 5y ago
  I often get robocallers that call twice if I don't answer the first time. I guess because most people assume two calls is an urgent matter and they REALLY want you to pick up. My low tech solution is to never answer calls from numbers that aren't in my contacts list. Everyone else can leave a voicemail.
  - mindslight 5y ago
    Wow, that's rough. I definitely don't get those. I think despite the obvious enumerability of phone numbers, most spam must be done off targeted lists. I've got a few SIP trunks with newly obtained numbers, and they don't really get spam.
onemoresoop 5y ago
Thing is, with robocalls, your a program is sequentially dialing numbers so even if you never share your phone number with anyone you'd still get robocalled. It's not very hard to guess a valid number whereas trying to build valid emails via brute force is not possible in the same way.
- walrus01 5y ago
  That is true and I cannot avoid the robocalls which are dialing a whole block of almost 10000 numbers in an NPA-NXX. Generally I don't answer unknown numbers since almost anyone that needs to reach me is either in my contact list, will reach me by Signal or another method, or I already know to expect a call from them. Of course this doesn't eliminate the possibility of receiving an incoming call from spoofed caller ID that is a perfect 1:1 match with an existing entry in my address book, but that's quite rare. I can only avoid the ones that are the result of some 3rd party that has an entry for me as firstname,lastname,phonenumber in some CRM system for marketing database. It does help a lot on the targeted calls.
  - lalaland1125 5y ago
    Seems like in theory this could be solved by having your asterisk system connect the call. Then block all numbers on your phone except your system.
    - walrus01 5y ago
      It could, I'm not quite ready to take that step yet. Or I could use exclusively a SIP softphone (zoiper) on my android phone to connect directly to my asterisk system as an extension, and only accept calls on that, which would come from the incoming filter call flow. The downside of that is that phone calls wouldn't work when in very marginal data coverage/rural areas, since voip-over-LTE-data relies on a fairly solid and packet loss free network connection, and the additional battery drain of maintaining a persistent sip client-to-server session on the phone all the time. I do have several extensions set up in zoiper for other purposes but I don't keep it running all the time.
jonpurdy 5y ago
I literally do the same thing, except "press 1 if you are a human". I haven't had any robocalls get through. I don't have a direct cell number as I just use a cheap data-only iPad plan with my iPhone only, combined with a VoIP iOS client (Bria). I use VoIP.ms for my service. It's basically hosted Asterisk with a nice web UI on top, as well as purchasing and managing DIDs. Related, I used this system for a condo buzzer when I lived in a building a few years ago. Set my name on the condo dialer to ring a specific DID for the condo buzzer to call, pointed towards VoIP.ms IVR, then just played DTMF 9 repeatedly to unlock the door and let them in. I triggered an SMS to send to me when this occurred so I'd know when someone was downstairs on their way up. Massive security hole, but not exploited once the entire time (except by me a few times when I forgot my keys).
- btown 5y ago
  The condo buzzer idea is legendary! I feel like you could have also waited for a reply to the SMS, or an interaction with a push notification via an app like pushsafer.com, so you could unlock the door from your phone!
  - walrus01 5y ago
    the buzzer system may not wait 'on the line' very long because it's expecting to receive either a DTMF tone for unlock door within 5 to 15 seconds of the call being answered, or a disconnect such as if a person in their condo is holding a POTS phone and just hangs it up when an unknown person buzzes them, denying entry.
    - jonpurdy 5y ago
      That’s correct, waiting for a push + acknowledgement would be too long which is why it just automatically does it. I did the push so I’d be able to track unexpected usage and there wasn’t a single one the entire time.
- walrus01 5y ago
  you set it up so that the IVR announcement WAV file you uploaded was a recording of the DTMF tones for "9" repeatedly? so basically anyone that pressed your buzzer number would get auto-entered into the building?

gruez 5y ago

Does this system pass through the original caller's info on caller id?

walrus01 5y ago
yes, it preserves caller ID on the outbound call initiated on the SIP trunk, my wholesale voip provider allows me to pass CID on outbound calls.

h0l0cube 5y ago

Seems like something people would pay for.

walrus01 5y ago
I have been thinking about turning it into a small project people can pay for, would first want to set up a series of scripts that could auto-provision everything immediately upon payment. Right now it's all manual since I'm the only person with the equivalent of admin/root on the asterisk system, and I've customized it for only my needs and those of my spouse.
- h0l0cube 5y ago
  It certainly doesn't sound like a trivial project, but given the preponderance of spam calls these days it seems like perfect timing for a product like this.
- Scoundreller 5y ago
  Should be able to do it all through VoIP.ms subaccounts. Complexity would be having to port in phone numbers (around here, that auto cancels your cellular account!), but see my other post, people could forward all calls to the server and proven humans would ring a soft phone.

gnicholas 5y ago

Can you provide more details about how you set this up? Does it provide a similar benefit to using Google Voice with call screening enabled? If my phone number is already out in the wild (apparently), is there anything I can do at this point? Or is the only solution to get a new phone number, never give it to strangers, and only give out a virtual number with screening?

walrus01 5y ago
It's related to what I do for work so what I've done I would not recommend to everyone... It's a FreePBX/Asterisk VM (CentOS 64-bit) that runs on a system in colocation somewhere at a major traffic exchange point. It is one of a number of VMs that run my personal infrastructure. It has a SIP trunk to a wholesale voip provider, where several DIDs reside. The incoming calls to the DIDs first hit my SIP trunking provider, which sends the incoming call signals to my voip server, which processes the call flow by starting with the IVR announcement I previously described. It is generally the same idea as google voice with call screening but I have approached it from a DIY perspective where I want to have full admin access over everything, except at the SS7/PSTN level where the DIDs are at my SIP trunking provider. Everything related to the incoming and outgoing calls I can customize for other unique purposes.
- gnicholas 5y ago
  Thanks! The more I read HN, the less I realize I know!
Scoundreller 5y ago
One way to do this without setting up a server or moving your phone number to another provider: 1. setup an unconditional redirect for all calls on your cell phone to a voip.ms DID that you set up ($1/month). This redirect functionality is baked into the gsm system: https://www.geckobeach.com/cellular/secrets/gsmcodes.php https://www.geckobeach.com/cellular/secrets/gsmcodes.php 2. On voip.ms, setup an IVR with a recorded message. Set it up to connect extension “1-2-3-4” or whatever your code is to your softphone. You should be able to whitelist numbers to auto-forward to your soft phone. Cool thing is you can setup voicemail through this so you receive them as email attachments. SMS still works through your cell phone. Outgoing calls still go through your cellphone.

mindslight 5y ago

I do greylisting. The first call from an unknown number plays asterisk standard recordings - SIT + "please try again". A successive call from the same number rings through. Legitimate callers have had no problem. I set it up this way because it was originally operating on a landline "in parallel" so that if the server failed the phones would still work. Next up is some kind of system that takes calls from places that you can never reach directly and instead call you back at bleeding-eyes-o'clock (eg doctors' offices), answers the call, and puts the caller on hold while I wake up. "Bucket of stomach fluid" can be a two way street.

bityard 5y ago
I often get robocallers that call twice if I don't answer the first time. I guess because most people assume two calls is an urgent matter and they REALLY want you to pick up. My low tech solution is to never answer calls from numbers that aren't in my contacts list. Everyone else can leave a voicemail.
- mindslight 5y ago
  Wow, that's rough. I definitely don't get those. I think despite the obvious enumerability of phone numbers, most spam must be done off targeted lists. I've got a few SIP trunks with newly obtained numbers, and they don't really get spam.

onemoresoop 5y ago

Thing is, with robocalls, your a program is sequentially dialing numbers so even if you never share your phone number with anyone you'd still get robocalled. It's not very hard to guess a valid number whereas trying to build valid emails via brute force is not possible in the same way.

walrus01 5y ago
That is true and I cannot avoid the robocalls which are dialing a whole block of almost 10000 numbers in an NPA-NXX. Generally I don't answer unknown numbers since almost anyone that needs to reach me is either in my contact list, will reach me by Signal or another method, or I already know to expect a call from them. Of course this doesn't eliminate the possibility of receiving an incoming call from spoofed caller ID that is a perfect 1:1 match with an existing entry in my address book, but that's quite rare. I can only avoid the ones that are the result of some 3rd party that has an entry for me as firstname,lastname,phonenumber in some CRM system for marketing database. It does help a lot on the targeted calls.
- lalaland1125 5y ago
  Seems like in theory this could be solved by having your asterisk system connect the call. Then block all numbers on your phone except your system.
  - walrus01 5y ago
    It could, I'm not quite ready to take that step yet. Or I could use exclusively a SIP softphone (zoiper) on my android phone to connect directly to my asterisk system as an extension, and only accept calls on that, which would come from the incoming filter call flow. The downside of that is that phone calls wouldn't work when in very marginal data coverage/rural areas, since voip-over-LTE-data relies on a fairly solid and packet loss free network connection, and the additional battery drain of maintaining a persistent sip client-to-server session on the phone all the time. I do have several extensions set up in zoiper for other purposes but I don't keep it running all the time.

jonpurdy 5y ago

I literally do the same thing, except "press 1 if you are a human". I haven't had any robocalls get through. I don't have a direct cell number as I just use a cheap data-only iPad plan with my iPhone only, combined with a VoIP iOS client (Bria). I use VoIP.ms for my service. It's basically hosted Asterisk with a nice web UI on top, as well as purchasing and managing DIDs. Related, I used this system for a condo buzzer when I lived in a building a few years ago. Set my name on the condo dialer to ring a specific DID for the condo buzzer to call, pointed towards VoIP.ms IVR, then just played DTMF 9 repeatedly to unlock the door and let them in. I triggered an SMS to send to me when this occurred so I'd know when someone was downstairs on their way up. Massive security hole, but not exploited once the entire time (except by me a few times when I forgot my keys).

btown 5y ago
The condo buzzer idea is legendary! I feel like you could have also waited for a reply to the SMS, or an interaction with a push notification via an app like pushsafer.com, so you could unlock the door from your phone!
- walrus01 5y ago
  the buzzer system may not wait 'on the line' very long because it's expecting to receive either a DTMF tone for unlock door within 5 to 15 seconds of the call being answered, or a disconnect such as if a person in their condo is holding a POTS phone and just hangs it up when an unknown person buzzes them, denying entry.
  - jonpurdy 5y ago
    That’s correct, waiting for a push + acknowledgement would be too long which is why it just automatically does it. I did the push so I’d be able to track unexpected usage and there wasn’t a single one the entire time.
walrus01 5y ago
you set it up so that the IVR announcement WAV file you uploaded was a recording of the DTMF tones for "9" repeatedly? so basically anyone that pressed your buzzer number would get auto-entered into the building?