I never activated on the tiered line. When I got my iPhone 6+, I called the activation number and told her I wanted to activate my new phone on a different line. CSR asked for the mobile number that I wanted the phone activated on, asked for the IMEI and ICCID (sim card) which both numbers can be found on the enclosed receipt that you receive with your new phone. I had to set up phone as new but later restored my phone from iTunes backup of my previous iPhone 5. I was able to keep my unlimited data. My line is still Month to Month. My tiered line has the contract date ending 2 years later from my shipped date.