Yes. Federal law (FCC porting rules) requires your current carrier to release your number to a new provider. They cannot refuse the port, even if you're mid-contract, even if you owe them money. Losing your number is never a reason to stay with a provider you've outgrown.
How it works: your new provider files the port with your old carrier using an account number and a PIN or recent bill copy. The transfer takes about 1-3 weeks for landlines, faster for mobile numbers. Your phone keeps working the entire time, and callers never notice the change.
The one way businesses DO lose numbers: cancelling old service before the port completes. A cancelled number goes back to the carrier's pool and may be unrecoverable. The rule is simple, port first, cancel after. A competent provider sequences this for you.
Also portable: toll-free numbers, fax numbers, and whole blocks of lines. And if your number is tied up in a carrier bundle (phone + internet), it can still port out; the carrier just reprices the remaining services, worth checking before you commit.
At 815 Voice porting is free and we handle the whole sequence. It's the first thing we set up, not an afterthought.