Deleted number

My 2nd phone Sim was deleted off the network due to non usage. I am trying to save, plus keep the phone off most of time as it receives a lot of spam. I've had this nr for 20 years. No warning, nothing. Just try to use it... And nothing. So, even if it was recycled into system, I should be able to simswap to activate it, no one else is using it, as the message says "this nr does not exist". Not only does all my records have that as secondary number, but I've pumped a goodly amount of money into that Sim over the past 20 years! This is really ridiculous!