Yes you can. Once the number is completely ported over to the new carrier, your line with T-Mobile will be cancelled. You will then have 90 days to resume the line, but after 60 days you will need a new SIM. When you are ready to resume the line, call into Activations and let them know you want to resume the line with a new number. They will get the line resumed and adjust the contract end date to the original contract end date (plus the number of days the line was cancelled for).