If it is locked, the answer probably is yes. But the service desk of the new provider can do that.
And remember that unlocking doesn't mean you don't have to pay them any more. If you have a 2-year contract, that's not yet finished, you keep paying until the end of the contract, even if you use another provider.
Kees
If I want to change to another mobile service provider and keep my number, does my PAYG phone have to be unlocked from the existing provider to allow the changeover?

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