The short answer
Use bands as a compatibility check, then judge the network by local coverage, capacity, and the exact device implementation.
Step by step
Find the phone's exact regional model number and its supported 4G and 5G bands.
Compare those specifications with the destination carrier's current compatibility requirements.
Understand the tradeoff: lower frequencies generally reach farther, while higher frequencies can add capacity over shorter distances.
Check whether the phone supports the carrier's voice, aggregation, and software requirements in addition to raw band numbers.
Run the IMEI checker and complete a local service test before committing.
Before you finish
Keep screenshots, receipts, chat transcripts, confirmation numbers, and the first bill after a change. Carrier terms and account eligibility can change, so verify the final price and conditions directly before submitting an order.