moved sim to new phone, now old phone thinks it is stolen

Hi recently upgraded my phone from an s3 to s5 and upon putting my sim in my new phone…my old phone now thinks its stolen.

I have to access my old phone for all contacts and the number i set up for it to send the pin to is my EX soooo i cant access it, I logged in online and declared the pone found, and diconnected my account but its still blaring off a siren and asking me for a pin??

What do i do :frowning: