Welcome to Android Central. If you don't have a SIM you don't have mobile data which is required to download OTA. Unless you have wifi? Also, are you sure you can upgrade your Ace? This may help:
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I've used a few phones without a SIM, or active service, over the years and they typically will get updates if updates are pushed out. It may take a little longer than the activated phones, but they still do come through over WiFi only. I've had Samsungs, LGs, Motorolas and Honor phones receive OTAs like this.
2.3 is the last update Samsung published, so if you're at 2.3, there are no more updates. Check the Area51 Forum to see if they have any later modifications. (Flagship phones are updated for 2 versions. Non-flagship phones - and the Ace is one - may get only a few security updates then, when the new version of Android comes out, the manufacturer won't rewrite it for that phone any more. Remember, Samsung has to rewrite every version of Android for every phone it wants that version to run on. Besides, even Jellybean would be a bit much to run on an Ace. It has only 158MB of storage and only 278MB of RAM.)