Mobile Phone Problem

[paul1763]

Partner and I both had iPhone 4s until last week,hers 8G mine 16G. I've now got iPhone 6S plus and given her my old 16G phone also we both switched providers, her from orange to ID me from BT to ID. We have several contacts common to us both. Since we've have swapped phones about, when someone phones me from our joint group my phone rings and hers shows the same number that I'm talking to. Also just now we called each other and hers showed my name and when she called me my screen showed "her name or my number" l can't work out what's happening as we both have new SIM cards. Any help appreciated. Thanks

[woofgang]

Did you set the phone up as a new phone via itunes?

[paul1763]

Hi woofgang, thanks for quick reply, no I didn't set up as new phone via iTunes, do I have to and is this easy to do?

[woofgang]

yes and yes.
https://support.apple.com/en-gb/HT204686