A calling app that displays the time in the destination city and, if between the hours of perhaps 11pm and 6am, pauses and asks if you want to proceed.
-- whatrock, Nov 29 2022

Structure of US cellphone numbers https://xkcd.com/1129/
[a1, Nov 29 2022]

"The person you are calling is 3 hours ahead of you. Do you still want to make this call?" [+]
-- 21 Quest, Nov 29 2022


What if the destination is not in a city?
-- pocmloc, Nov 29 2022


There's no sure way to tell where the destination phone is. A lot of people keep their cellphone number (including area code) when they move.
-- a1, Nov 29 2022


Cell phones know which cell they are connected to, & that has a location accurate enough for this idea. (I'm assuming you dial, then the message happens, before the recipient phone rings (or not).)
A satellite phone could be a problem, unless those have a GPS function tagged to the call data.
-- neutrinos_shadow, Nov 30 2022


It would probably require a permission setting to be enabled on both user's phones, similar to sending/requesting read receipts for SMS.
-- 21 Quest, Nov 30 2022


// cellphone know which cell the they're connected to //

Fair enough, I was thinking it would just guess from NPA-NXX lookup. But assuming it can route the call and the network can tell the caller where the destination is quickly and without ringing, this could work. Law enforcement would love it too. They’d never have any trouble covertly tracking someone's phone with this, right? Solve a lot of missing person cases, track bad guys without a court order, etc.
-- a1, Nov 30 2022



random, halfbakery