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

"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


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



random, halfbakery