For smartphone-only apps that require each user to be a person (apps where there is no room for people to have multiple accounts), what are the negative consequences of limiting each phone number to one account creation? Assume that the logistics behind people changing their numbers and preserving their accounts is handled gracefully, does the concept of limiting one account per number pose a significant hindrance in any way? I don't know any people who share a mobile number or a phone, but that "data" is purely speculative and anecdotal--maybe lots of people do?

The purpose of this policy is spam prevention.

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    Another option you have is to tie the app to the store account, as several games on Google's Play Store/ Apple's app store do. This is more natural for non-messenger apps.
    – T. Sar
    Dec 10, 2018 at 11:16
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    Sharing phones among multiple users probably isn't that common (though, like you, I have no data), but I imagine sharing a tablet is more common. From the little I've seen, later versions of Android allows multiple users/profiles to exist (so, presumably, each users' details are kept separate) and I would guess iOS may do something similar. However, with many/most tablets you wouldn't have a phone number so you'd have to use the store-account or whatever as the ID.
    – TripeHound
    Dec 10, 2018 at 15:16
  • fyi: there are throwaway phone number services just like there are throwaway email services. e. g. smsreceivefree.com (phone) and 10minutemail.com (mail)
    – BlueWizard
    Dec 11, 2018 at 12:56
  • @BlueWizard good phone-verification APIs, like TeleSign, will not authenticate those kinds of numbers. Basic email verification is completely useless for spam prevention because of how easy email accounts are to get in large amounts. In the practical sense, all email verification does is require genuine users to take an extra registration step. At that point, for a quicker registration experience, just have no verification... unless if you're requiring specific email domains like gmail that often require a phone number.
    – user121402
    Dec 11, 2018 at 13:20
  • As someone who is successfully puppeteering multiple gmail accounts let me tell you: don't waste your time with extended verification. People are not applying to be the next James Bond. Instead they just want to use your service.
    – BlueWizard
    Dec 11, 2018 at 15:21

1 Answer 1


Well, one of the consequences is that you'll lose users who are not willing to share their phone number with you. I think I've shared my phone number and contacts list with only one app (WhatsApp); for a messenger app, it definitely makes sense to have those details. For other apps, not so much, and I'd rather not share sensitive data like my phone number with them.

  • Nowadays, users complain as much about spam and bots as developers do. And, unfortunately, there is not yet a better safeguard against spam in mobile than the phone verification--it works on all devices (and all os versions) and it can filter out seedy numbers by their type, their carrier, and how often they register with other apps. And I think users get that, and I think they're willing to give up their numbers because of it. And in my case, they may have to. I think your level of resistance to share your number puts you in a very small minority of the total userbase, don't you?
    – user121402
    Dec 11, 2018 at 7:18
  • Yeah I'm one of these users who is not willing to give apps access to my phone number.
    – BlueWizard
    Dec 11, 2018 at 12:54
  • @BlueWizard if a proposition was made to you at registration that your number would be used exclusively for account creation, and nothing else, and that doing so would potentially reduce fake accounts by 99% (dramatically improving your UX), would you then consent?
    – user121402
    Dec 11, 2018 at 13:28
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    You don't want to argue with every individual user (i am an individual). But you can accept the fact that "there are people like user Glorfindel or user BlueWizard who would not enter their phone number". I don't understand why my experience with your service should improve so greatly when there are no fake accounts. Can you clarify the question by extending it? For example what does you app do? Does it show alcohol (protecting minors) or is it used for granting loans / selling things / dating?
    – BlueWizard
    Dec 11, 2018 at 15:31

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