Please can anybody advise how it all works with iphone contacts and storage. Bet it's a simple explanation but need to suss it to sort it out.
Basically, my misses had an iphone 4 which she upgraded to an iphone 6S when her contract run out. That was well over a year ago. She kept her old number but used a new SIM card in the 6.
My sister in law bought the 4 and was able to utilise her original SIM card. I'm know for sure that the original SIM card did not go with the 4 when she took it over. Since activating the 4, my wife's numbers have appeared in my sister in laws contacts and vice versa. Also, some of the photos taken on the 6 less than a month ago have appeared on the 4's storage. Need to check but believe they could be viewed on the 4.
My thinking is that all this is icloud related but not sure. Also, on my Antroid driven basic motorola smart phone there is a 'migrate' feature for obtaining existing numbers. Not sure if a similar system is utilised on iphone OS operating system, but this may have something to do with the cross contamination on the two iphones.
Any advice gratefully received.