6 ms·

Microsoft Teams is the reason some Android users can't dial 911

34 points by wyrm 5y ago

montroser 5y ago
They mention a fix in the works for the Teams app, but the bigger story here seems a fundamental problem with Android, whereby simply installing an app can break your ability to place telephone calls.
- dbavaria 5y ago
  Without an OS fix, what stops a malicious app developer from intentionally implementing the "Teams bug"?
  - tssva 5y ago
    An OS level patch is also mentioned in the article.
e9 5y ago
None of that makes any sense. Code that handles emergency calls must be handled separately from anything else. Third party apps should not be able to affect it in any way. This just shows how reckless Android development is.
- ozfive 5y ago
  Completely reckless. Teams is terrible on Windows and Android. I'm not surprised. I only use it because my company has consumed the Kool aid. Otherwise I would never touch it. Slack forever!
- frosted-flakes 5y ago
  Doesn't Teams need to be able to make emergency calls? What if the phone has no cell service but it has an Internet connection? Dialling 911 must always connect to local emergency services, and I'm pretty sure Teams is not exempt from those rules.
  - eyelidlessness 5y ago
    The idea that this is something an app on a phone is responsible for is utterly terrifying to me. This should be handled by the OS, and completely isolated from apps so they can’t interfere or provide broken implementations.
    - frosted-flakes 5y ago
      The point is that Teams needs to handle emergency calling. What if someone uses a tablet as their phone? The OS can't always provide emergency calling capabilities. A tablet does not present itself as a phone by default, which is why it doesn't usually have a dialler. But if you install Teams or some other calling app, bam, it becomes a phone and needs to follow the law, and if someone opens the Teams app directly and dials 911, it still needs to connect. Maybe emergency calls from the OS dialler should only be allowed to be handled by the OS, but is it as cut-and-dry as it looks? Not always.
      - eyelidlessness 5y ago
        Why does Teams need to handle emergency calling? What is the mandate that says it does?
        frosted-flakes 5y ago
        I believe it is called Kari's Law. Anything that presents as a phone needs to be able to handle emergency calls, or something to that effect. Edit: I'm not super familar with it, it's just something I remember reading before. It might not be Kari's Law exactly, as that seems to be more for Multiline Telephone Systems, such as in hotels or offices. Maybe I'm totally wrong and calling apps like Teams don't need to handle emergency calls and they simply choose to, but I'm pretty sure they are required to.
        eyelidlessness 5y ago
        Wouldn’t it be better for apps on mainstream OSes to be both able and required to use OS facilities for that? I mean, it’s not as if Android doesn’t have a solution for this. Why should Android apps have to (redundantly and almost certainly incorrectly) implement this when the OS already does? Yeah a tablet isn’t a phone. But it’s running a phone OS.
ozfive 5y ago
This page on Androidpolice.com crashes my mobile chrome browser. Won't be going to that site again.
greenyoda 5y ago
There was a huge discussion yesterday of the original Reddit post: https://news.ycombinator.com/item?id=29492884 https://news.ycombinator.com/item?id=29492884 And today, a very detailed technical analysis of the multiple bugs in Android and Teams that caused the issue: https://news.ycombinator.com/item?id=29513795 https://news.ycombinator.com/item?id=29513795
- zamalek 5y ago
  TL;DR: Subtraction was used for comparison (an optimization trick that nearly always works). We all make mistakes, but here's a great example of why not to go branchless, especially outside of a hot path.
olliej 5y ago
No, the problem is android - a single app being able to block emergency calls in any situation for any reason is an OS bug.

34 points by wyrm 5y ago

They mention a fix in the works for the Teams app, but the bigger story here seems a fundamental problem with Android, whereby simply installing an app can break your ability to place telephone calls.

dbavaria 5y ago
Without an OS fix, what stops a malicious app developer from intentionally implementing the "Teams bug"?
- tssva 5y ago
  An OS level patch is also mentioned in the article.

e9 5y ago

None of that makes any sense. Code that handles emergency calls must be handled separately from anything else. Third party apps should not be able to affect it in any way. This just shows how reckless Android development is.

ozfive 5y ago
Completely reckless. Teams is terrible on Windows and Android. I'm not surprised. I only use it because my company has consumed the Kool aid. Otherwise I would never touch it. Slack forever!
frosted-flakes 5y ago
Doesn't Teams need to be able to make emergency calls? What if the phone has no cell service but it has an Internet connection? Dialling 911 must always connect to local emergency services, and I'm pretty sure Teams is not exempt from those rules.
- eyelidlessness 5y ago
  The idea that this is something an app on a phone is responsible for is utterly terrifying to me. This should be handled by the OS, and completely isolated from apps so they can’t interfere or provide broken implementations.
  - frosted-flakes 5y ago
    The point is that Teams needs to handle emergency calling. What if someone uses a tablet as their phone? The OS can't always provide emergency calling capabilities. A tablet does not present itself as a phone by default, which is why it doesn't usually have a dialler. But if you install Teams or some other calling app, bam, it becomes a phone and needs to follow the law, and if someone opens the Teams app directly and dials 911, it still needs to connect. Maybe emergency calls from the OS dialler should only be allowed to be handled by the OS, but is it as cut-and-dry as it looks? Not always.
    - eyelidlessness 5y ago
      Why does Teams need to handle emergency calling? What is the mandate that says it does?
      - frosted-flakes 5y ago
        I believe it is called Kari's Law. Anything that presents as a phone needs to be able to handle emergency calls, or something to that effect. Edit: I'm not super familar with it, it's just something I remember reading before. It might not be Kari's Law exactly, as that seems to be more for Multiline Telephone Systems, such as in hotels or offices. Maybe I'm totally wrong and calling apps like Teams don't need to handle emergency calls and they simply choose to, but I'm pretty sure they are required to.
        eyelidlessness 5y ago
        Wouldn’t it be better for apps on mainstream OSes to be both able and required to use OS facilities for that? I mean, it’s not as if Android doesn’t have a solution for this. Why should Android apps have to (redundantly and almost certainly incorrectly) implement this when the OS already does? Yeah a tablet isn’t a phone. But it’s running a phone OS.

ozfive 5y ago

This page on Androidpolice.com crashes my mobile chrome browser. Won't be going to that site again.

greenyoda 5y ago

There was a huge discussion yesterday of the original Reddit post: https://news.ycombinator.com/item?id=29492884 https://news.ycombinator.com/item?id=29492884 And today, a very detailed technical analysis of the multiple bugs in Android and Teams that caused the issue: https://news.ycombinator.com/item?id=29513795 https://news.ycombinator.com/item?id=29513795

zamalek 5y ago
TL;DR: Subtraction was used for comparison (an optimization trick that nearly always works). We all make mistakes, but here's a great example of why not to go branchless, especially outside of a hot path.

olliej 5y ago

No, the problem is android - a single app being able to block emergency calls in any situation for any reason is an OS bug.