I have had a GSM sim for a year and it was never even been placed in a device. It has not been suspended but the $0.01 fee was charged this month. Given this outrageous price gouging for a service I do not use, I think I will cancel the account.
One of my LTE sims went to sleep. I woke it up and the number was gone. I've had it fall asleep several times before but this is the first time the number has been removed. I tried to get a new number and the closest area code is 600+ miles away.
I was going to use it to port in somewhere else for one of the free year or $1 a year deals. Just my luck.
My situation is just the opposite. I ported 3 numbers to Sprint and Virgin Mobile and I can still see these numbers in my FP accounts. If I login to FP app I can still call out with those numbers. I will wait a year to see if they are still there.
Since you won't be able to receive incoming calls and the outgoing calls will continue to use VOIP I suspect that you'll retain the ability to use those numbers indefinitely.