https://forums.crackberry.com/blackberry-z3-f418/blackberry-z3-sim-card-not-detected-why-1068435/
Have you confirmed the SIM itself is OK - put the SIM in another phone (either unlocked or on the same network) or putting another SIM in your phone (Any network if your phone is unlocked or same network if not)
http://support.blackberry.com/kb/#q=z3%20sim%20not%20detected
https://forums.crackberry.com/blackberry-z3-f418/why-my-blackberry-z3-not-detecting-any-sim-card-1051547/
https://forums.crackberry.com/blackberry-z10-f254/sim-card-not-detected-791158/
https://www.wikihow.com/Fix-a-Sim-Card-Error-on-a-Blackberry
https://mindaschool.blogspot.com/2017/10/blackberry-z3-simcard-not-detected-insert-sim-card-sim-way.htm - A bit cryptic though
affaagws
February 2018