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What I don’t understand is why no major mobile carrier is offering a solution to this. It’s a pretty competitive market and this could be a big selling point.

What I don’t understand is why no major mobile carrier is offering a solution to this. It’s a pretty competitive market and this could be a big selling point. When the isp wars were going strong, before broadband put everyone under the thumb of monopolists and also before gmail, spam filtering was a serious competative advantage. Why can’t phone companies take an RBL like approach? If your VoIP service garners too many complaints because you are selling to robocallers then you don’t get to have calls delivered to e.g. ATT mobile customers anymore? Are there legal or technical interconnection requirements that would make such a thing impossible?

mikeash 9y ago
AT&T has a Call Protect app which attempts to do this. It misses some, but my spam call volume has dropped quite a bit with it.
- rconti 9y ago
  Thanks, looking into it now. iOS and Android app. I'm curious to see how this works. Probably can't get in the way of the calls on the device itself; pushes changes to the network maybe? https://www.att.com/features/security-apps.html https://www.att.com/features/security-apps.html
  - mikeash 9y ago
    Some of it is just a matter of associating the name “Telemarketer” with a phone number. I still see those calls, but can immediately identify them. Stuff it’s more confident about gets blocked outright. I think they’re automating what they’d do if you went into your account and manually blocked a number.
    - rconti 9y ago
      I already have a /dev/null contact with a silent ringer but the telemarketers (especially the neighbor dialing) almost never uses the same number twice. Still hopeful the ATT app helps though.
      - mikeash 9y ago
        Their list automatically updates based on whatever mysterious processes happen in their end, so it should be an improvement over manually blocking numbers after you get a spam call. Hopefully it will help a little bit. It's definitely not a cure, but we have to take what we can.
- exhilaration 9y ago
  I get almost no spam calls now, Google has call spam blocking built into Pixel phones and I went from a few spam calls a week to maybe 1 or 2 a month. And those 1 or 2 calls ring with a red warning that they're potential spam calls. For reference, I've had the same New Jersey mobile number since 2001.
  - joecool1029 9y ago
    I believe it's an Android Oreo feature, not specific to the Pixel. I picked up a Nokia 6 for my dad and was surprised to see it blocking. Google Voice has had spam lists forever, it's likely they are pooling the data from there. T-Mobile does have the ScamID/block thing that can be controlled by shortcode. Documentation here https://explore.t-mobile.com/callprotection https://explore.t-mobile.com/callprotection
pboutros 9y ago
I think the answer is that it is not a pretty competitive market. The two biggest carriers have a 1-2% monthly churn rate. https://www.statista.com/statistics/283511/average-monthly-churn-rate-top-wireless-carriers-us/ https://www.statista.com/statistics/283511/average-monthly-c...
- hunter23 9y ago
  2% monthly churn is not low. That annualizes to ~25% which is significant. The cost per acquisition of getting a new customer is actually quite high so their churn numbers definitely hurt them.
  - kingnothing 9y ago
    When there are only 4 carriers in the US, it doesn't really matter. AT&T will lose a customer to Sprint, Sprint loses one to T-Mobile, T-Mobile loses one to Verizon, and Verizon loses one to AT&T. No one is getting rid of their cell phones.
    - rtkwe 9y ago
      The point is they still have to spend the money to make keep their flows positive otherwise they'll bleed customers to the other 3 and die eventually.
rayiner 9y ago
Blocking calls from certain VoIP services is almost certainly going to be a violation of common-carrier rules (which still apply to phone service no matter what happens with broadband). At a technical level, spam filtering relies heavily on analyzing email text. Doing similar analysis on voice calls is way harder. Also, there's UI issues. You can redirect suspected spam emails to a folder the user can inspect for false positives. What do you do with a call that hits the robocall filter?
- buckminster 9y ago
  Worse than that, international telecommunications are governed by treaties and the ITU. There is much bureaucracy in the way of a fix.
- bradleyjg 9y ago
  Later on spam filtering relied on analyzing email text, but before that was available there was the blunt instrument of blackholing ISPs that refused to police their users. That approach could work here.
  - rayiner 9y ago
    I remember Bayesian spam filters being the first widely used ones. But it was a long time ago. It’s not clear to me that carriers would be allowed to do that, especially accounting for situations where VoIP traffic is laundered through a legitimate service (so the entity at the exchange boundary with the end-user carrier is a legitimate one). Could they get around common carrier restrictions by offering that service as opt in? I’m not so sure about that either.
- afo 9y ago
  Actually, the FCC clarified their rules a few years back that carriers CAN block robocalls. More details here: https://www.broadcastingcable.com/news/fcc-clarifies-robocall-rules-141868 https://www.broadcastingcable.com/news/fcc-clarifies-robocal... Note that Ajit Pai (then a commissioner, not chairperson like now) voted AGAINST this. Full disclosure: We (Nomorobo) advocated to the FCC to allow carriers to block robocalls.
nikanj 9y ago
Should be technically possible to have ”these numbers can originate from this operator”. I’ve learned that if a phone looks to be from my area code, it’s actually from China. No idea what the robocaller is saying. My operator should be able to have a short list of teleoperators in this zip code, and drop other calls.
- c22 9y ago
  I've had the same phone number for over 20 years now, since LNP became a thing I've moved it a couple of times to different providers. Most recently I've parked it with a non-local voip provider which gives me a great deal of flexibility. It sounds like under your proposal no one would receive my calls?
  - nikanj 9y ago
    No matter what solution is proposed, there's always a subset of people who depend on that very behavior (see https://xkcd.com/1172/ https://xkcd.com/1172/ ). I think no-one receiving calls from parked non-local voip numbers would be an acceptable price to pay for the elimination of voip spam. You are free to disagree, tech is all about making compromises. Incidentally, this quickly follows the path we took with SMTP. I can no longer telnet into a random SMTP server and dump incoming mail, which no doubt ruined the carefully honed scripts of many sysadmins.
- reaperducer 9y ago
  Something that helps is having an "undesirable" area code. Telemarketers have learned that certain area codes convert at much higher rates than others. 202, 203, 212, 213 are prime targets. 242, 246, 406 and 701? Notsomuch. If your NPA isn't important to you, get a number in those areas. (Some carriers will let you choose your area code as long as you're within the same billing center.)
  - ghostly_s 9y ago
    I'm feeling very grateful for sticking with the same phone number I've had since high school in rural Minnesota. 100% of numbers I receive from "my" area code that aren't my mother, are spam. :)
acdha 9y ago
T-Mobile offers it as a free option with two levels: labeling the call as Scam Likely and blocking it outright. The latter is quite effective - I was getting 5+ calls per day and it’s now 1-2 per week.
- s73v3r_ 9y ago
  That's T-Mobile? I thought it was Google Voice.
  - r00fus 9y ago
    Definitely TMO - it's on the billing statement (free line item).
    - kevin_thibedeau 9y ago
      Only for postpaid accounts. T-mobile treats its prepaid customers like garbage. They even refuse to register correct callerID info for numbers they assigned in violation of E911 requirements.
- joemag 9y ago
  The “Spam Likely” determination is fairly unreliable, IMO. They have labeled my doctors office “Scam Likely”, while many “Scam definitely” calls have not been labeled.
  - StudentStuff 9y ago
    T-Mobile's handling of "Scam Likely" seems to be spotty at best, with quite a few false positives. Additionally, their 3rd party vendor seems to be wanting to audit businesses that are mis-identified: https://feedback.fosrvt.com/ https://feedback.fosrvt.com/
  - kolpa 9y ago
    Is it perhaps because scammers have impersonated your doctor's phone number?
JustSomeNobody 9y ago
> What I don’t understand is why no major mobile carrier is offering a solution to this. Carriers have no economic incentive to do this. Most people on AT&T aren't going to jump to Verizon because of the number of robocalls they get on AT&T. It's not worth the hassle of changing.
reaperducer 9y ago
>What I don’t understand is why no major mobile carrier is offering a solution to this. I remember at one of the WWDC keynotes, Tim Cook announced this as a new iPhone feature. But he also noted that it was only available in China. I wonder if whatever the Chinese carriers have done can be imported to the United States. My wife's iPhone will occasionally get an incoming call with small text below reading "Possible spam." She never uses her phone for voice, so she never answers the phone anyway.
- afo 9y ago
  I found that strange, too. Apple made it seem like it was China only but it's not. Those features of CallKit are what we (Nomorobo) use to stop the robocalls.

mikeash 9y ago

AT&T has a Call Protect app which attempts to do this. It misses some, but my spam call volume has dropped quite a bit with it.

rconti 9y ago
Thanks, looking into it now. iOS and Android app. I'm curious to see how this works. Probably can't get in the way of the calls on the device itself; pushes changes to the network maybe? https://www.att.com/features/security-apps.html https://www.att.com/features/security-apps.html
- mikeash 9y ago
  Some of it is just a matter of associating the name “Telemarketer” with a phone number. I still see those calls, but can immediately identify them. Stuff it’s more confident about gets blocked outright. I think they’re automating what they’d do if you went into your account and manually blocked a number.
  - rconti 9y ago
    I already have a /dev/null contact with a silent ringer but the telemarketers (especially the neighbor dialing) almost never uses the same number twice. Still hopeful the ATT app helps though.
    - mikeash 9y ago
      Their list automatically updates based on whatever mysterious processes happen in their end, so it should be an improvement over manually blocking numbers after you get a spam call. Hopefully it will help a little bit. It's definitely not a cure, but we have to take what we can.
exhilaration 9y ago
I get almost no spam calls now, Google has call spam blocking built into Pixel phones and I went from a few spam calls a week to maybe 1 or 2 a month. And those 1 or 2 calls ring with a red warning that they're potential spam calls. For reference, I've had the same New Jersey mobile number since 2001.
- joecool1029 9y ago
  I believe it's an Android Oreo feature, not specific to the Pixel. I picked up a Nokia 6 for my dad and was surprised to see it blocking. Google Voice has had spam lists forever, it's likely they are pooling the data from there. T-Mobile does have the ScamID/block thing that can be controlled by shortcode. Documentation here https://explore.t-mobile.com/callprotection https://explore.t-mobile.com/callprotection

pboutros 9y ago

I think the answer is that it is not a pretty competitive market. The two biggest carriers have a 1-2% monthly churn rate. https://www.statista.com/statistics/283511/average-monthly-churn-rate-top-wireless-carriers-us/ https://www.statista.com/statistics/283511/average-monthly-c...

hunter23 9y ago
2% monthly churn is not low. That annualizes to ~25% which is significant. The cost per acquisition of getting a new customer is actually quite high so their churn numbers definitely hurt them.
- kingnothing 9y ago
  When there are only 4 carriers in the US, it doesn't really matter. AT&T will lose a customer to Sprint, Sprint loses one to T-Mobile, T-Mobile loses one to Verizon, and Verizon loses one to AT&T. No one is getting rid of their cell phones.
  - rtkwe 9y ago
    The point is they still have to spend the money to make keep their flows positive otherwise they'll bleed customers to the other 3 and die eventually.

rayiner 9y ago

Blocking calls from certain VoIP services is almost certainly going to be a violation of common-carrier rules (which still apply to phone service no matter what happens with broadband). At a technical level, spam filtering relies heavily on analyzing email text. Doing similar analysis on voice calls is way harder. Also, there's UI issues. You can redirect suspected spam emails to a folder the user can inspect for false positives. What do you do with a call that hits the robocall filter?

buckminster 9y ago
Worse than that, international telecommunications are governed by treaties and the ITU. There is much bureaucracy in the way of a fix.
bradleyjg 9y ago
Later on spam filtering relied on analyzing email text, but before that was available there was the blunt instrument of blackholing ISPs that refused to police their users. That approach could work here.
- rayiner 9y ago
  I remember Bayesian spam filters being the first widely used ones. But it was a long time ago. It’s not clear to me that carriers would be allowed to do that, especially accounting for situations where VoIP traffic is laundered through a legitimate service (so the entity at the exchange boundary with the end-user carrier is a legitimate one). Could they get around common carrier restrictions by offering that service as opt in? I’m not so sure about that either.
afo 9y ago
Actually, the FCC clarified their rules a few years back that carriers CAN block robocalls. More details here: https://www.broadcastingcable.com/news/fcc-clarifies-robocall-rules-141868 https://www.broadcastingcable.com/news/fcc-clarifies-robocal... Note that Ajit Pai (then a commissioner, not chairperson like now) voted AGAINST this. Full disclosure: We (Nomorobo) advocated to the FCC to allow carriers to block robocalls.

nikanj 9y ago

Should be technically possible to have ”these numbers can originate from this operator”. I’ve learned that if a phone looks to be from my area code, it’s actually from China. No idea what the robocaller is saying. My operator should be able to have a short list of teleoperators in this zip code, and drop other calls.

c22 9y ago
I've had the same phone number for over 20 years now, since LNP became a thing I've moved it a couple of times to different providers. Most recently I've parked it with a non-local voip provider which gives me a great deal of flexibility. It sounds like under your proposal no one would receive my calls?
- nikanj 9y ago
  No matter what solution is proposed, there's always a subset of people who depend on that very behavior (see https://xkcd.com/1172/ https://xkcd.com/1172/ ). I think no-one receiving calls from parked non-local voip numbers would be an acceptable price to pay for the elimination of voip spam. You are free to disagree, tech is all about making compromises. Incidentally, this quickly follows the path we took with SMTP. I can no longer telnet into a random SMTP server and dump incoming mail, which no doubt ruined the carefully honed scripts of many sysadmins.
reaperducer 9y ago
Something that helps is having an "undesirable" area code. Telemarketers have learned that certain area codes convert at much higher rates than others. 202, 203, 212, 213 are prime targets. 242, 246, 406 and 701? Notsomuch. If your NPA isn't important to you, get a number in those areas. (Some carriers will let you choose your area code as long as you're within the same billing center.)
- ghostly_s 9y ago
  I'm feeling very grateful for sticking with the same phone number I've had since high school in rural Minnesota. 100% of numbers I receive from "my" area code that aren't my mother, are spam. :)

acdha 9y ago

T-Mobile offers it as a free option with two levels: labeling the call as Scam Likely and blocking it outright. The latter is quite effective - I was getting 5+ calls per day and it’s now 1-2 per week.

s73v3r_ 9y ago
That's T-Mobile? I thought it was Google Voice.
- r00fus 9y ago
  Definitely TMO - it's on the billing statement (free line item).
  - kevin_thibedeau 9y ago
    Only for postpaid accounts. T-mobile treats its prepaid customers like garbage. They even refuse to register correct callerID info for numbers they assigned in violation of E911 requirements.
joemag 9y ago
The “Spam Likely” determination is fairly unreliable, IMO. They have labeled my doctors office “Scam Likely”, while many “Scam definitely” calls have not been labeled.
- StudentStuff 9y ago
  T-Mobile's handling of "Scam Likely" seems to be spotty at best, with quite a few false positives. Additionally, their 3rd party vendor seems to be wanting to audit businesses that are mis-identified: https://feedback.fosrvt.com/ https://feedback.fosrvt.com/
- kolpa 9y ago
  Is it perhaps because scammers have impersonated your doctor's phone number?

JustSomeNobody 9y ago

> What I don’t understand is why no major mobile carrier is offering a solution to this. Carriers have no economic incentive to do this. Most people on AT&T aren't going to jump to Verizon because of the number of robocalls they get on AT&T. It's not worth the hassle of changing.

reaperducer 9y ago

>What I don’t understand is why no major mobile carrier is offering a solution to this. I remember at one of the WWDC keynotes, Tim Cook announced this as a new iPhone feature. But he also noted that it was only available in China. I wonder if whatever the Chinese carriers have done can be imported to the United States. My wife's iPhone will occasionally get an incoming call with small text below reading "Possible spam." She never uses her phone for voice, so she never answers the phone anyway.

afo 9y ago
I found that strange, too. Apple made it seem like it was China only but it's not. Those features of CallKit are what we (Nomorobo) use to stop the robocalls.