I was wandering how this works programming wise.
If I log into my online banking website on my pc, As I login, the app on my android device popups up and lets me enter the OTP.
How do they achieve this without polling the server? As obviously the phones Ip will change all the time, depending which cellphone tower you are on, if you are on wifi etc.
I would really like to know how they went about implementing this, as I see it to be very useful.</div