Ask HN: Looking for Beta Testers for CallStop, a 100% Effective Robocall Blocker

It looks like this app is based on whitelisting. While this would indeed be 100% effective at stopping spam calls, it would also be 100% effective at stopping urgent calls from numbers that you're unfamiliar with. For example:

- A hospital or police department calling to tell you that your spouse has been injured in an accident.

- Your doctor calling you back from one of several outgoing lines in her office whose number you don't know.

Do you want to rely on these callers being able to figure out how to get through your spam blocker in an emergency? They're calling from landlines, so they also can't text you or receive a text from your app.

To solve this issue, I've included:

The ability to set PINs, which means people who know your number but aren't whitelisted can reach you at any time (think doctor, police, school, etc).

When you list your number on any form just include a PIN. You can add as many PINs as you want and include a description for each.

When calling a CallStop number, an unknown caller hears this default message:

"You have reached a phone number protected by CallStop. If you know this person, press 1 to send a whitelisting request with a quick note. If you have a PIN to reach this person directly, press 2 and enter the PIN."

How would the police who pulled your spouse from a car wreck know your PIN?

How would someone store your PIN in a contacts list that didn't include a field for a PIN?

This system places obstacles in the way of someone who may need to reach you urgently. Is that a good tradeoff to make for not receiving spam calls?

>>How would the police who pulled your spouse from a car wreck know your PIN?

You need to let organizations know a PIN. Later on, automated channels and PINs can be created that each user opts into--like whitelists for public services (police, government etc.). Those could work with automatic notifications/updates for those organizations. You could also opt in to whitelist certain numbers on signup (like public services) once SHAKEN/STIR is ready (so that commonly whitelisted numbers aren't spoofed). I understand I'm describing a long term solution and I'm being very idealistic here.

>>How would someone store your PIN in a contacts list that didn't include a field for a PIN?

PINs are for organizations and groups to store. Contacts are to be used more in scenarios with whitelisting. You may be able to store contacts with PINs that you can dial, but I haven't had time to play around with the pause functionality in Apple contacts yet. I think organizations will easily store PIN info.

>>This system places obstacles in the way of someone who may need to reach you urgently. Is that a good tradeoff to make for not receiving spam calls?

More than half of all calls are spam calls. In my mind it is. I used to get 5-10 spam calls every day. But, that's part of the reason I'm running this test :)

iOS 13 has a setting built-in that if it's on, it only allows calls through if they're in your contacts. Otherwise the calls go straight to voicemail and still show up in your recent calls.

I hope you know this. You can see this in the Beta builds.

I do. I've talked to lots of people and the problem with that solution is that if you work with large groups of people, they can't get through. That's why the PINs feature is useful. Lots of people work with supplies, business networks, etc so they can't just reject non-whitelisted people.

Also, whitelist requests are effortless with CallStop. I don't think Apple's solution has any concept of that.

There's a lot more that could be added to CallStop too. Think about limiting the number of times a certain number could call you (think your internet provider, etc.) and also automatically implementing time based rules (you can only be reached for work between hour x and hour y daily).

I'm curious how it works technically. I thought Apple did not allow Apps access to the phone functionality.

It doesn't need to have access to Apple's functionality.

Try pulling out your phone and dialing *72 followed by another number. It will forward your device calls to the number you dial.

That's the key here. You forward your device number to CallStop, which uses VOIP Pushkit to receive calls. In that way, each CallStop user can set code level rules on who can reach them and when. It's like a firewall for phone calls.

Here's a sample number you can call to try this out: 650-300-0574

You should be able to get a good idea of how the service works by selecting different options when calling it. Try pressing 1 and check out the text you get to add a whitelisting note, or 2 and try entering a PIN. CallStop users get push notifications for whitelist requests and rejected calls.

One of the cool implications if a service like this is adopted is that phone numbers for anyone can be public and it will no longer matter.

Will *72 forward SMS messages as well?

No. It's "call forwarding".

No, just phone calls. With CallStop: You receive incoming calls through CallStop. You can make outgoing calls as normal through the Apple app, and also I've added outgoing calling functionality into CallStop. Texts are not forwarded, though this is something I'm researching for future features. Text spam is the second thing to eliminate here.