Which agreement is changing?
An upgrade conversation can cover the handset, airtime, optional protection and subscriptions at once. Ask for the documents identifying each change. Write down what continues and what is replaced. If only the data allowance needs to change, a new phone may be a separate decision. A familiar account or an existing relationship does not remove the need to understand a fresh minimum term.
What happens to the old handset?
Establish whether you own it outright, owe a balance or must return it under the proposed arrangement. Where inspection determines value, ask which conditions affect the outcome and what happens if the assessment differs from the estimate. Keep dispatch and acceptance records. An invitation to upgrade does not prove that the existing device commitment has disappeared.
Which features are worth keeping?
Compare the new agreement with the features you actually use: roaming, hotspot activity, connected devices, call handling and support. A newer tariff can have different conditions from the old one. An extra that sounds attractive may require activation or later renewal. Check the end dates, not just the welcome period, so the comparison remains useful after the first month.
When is the decision ready?
It is ready when you can explain the device position, the service term and the effect on the current account in ordinary language. Keep the written summary that matches the exact choice. If a phrase remains unclear, ask the provider before accepting. General guidance can help translate the terminology, but cannot assess a credit application or authorise an upgrade on your behalf.
General practical explanation; confirm plan-specific rules with the provider.