To set expectations, there is a charge of $15 for the number change. On the other hand, since it is your first time to request for the mobile number change, this is waived by the system. Please see the advisements below and confirm: Please take your time reading and confirm. Thank you! You'll receive a free text message with the new mobile number. Once received, please turn your phone off, then back on. You may receive a free text message stating that your previous mobile number has been unenrolled from the service. Don't worry your service carries over to the new mobile number. 3.Mobile number changes are completed within 2 to 4 hours. Your voicemail box will be deleted, and all old messages will be lost, so make sure to save voicemails you wish to keep. Call records for the old phone number will no longer be available on My T-Mobile. Wait 24 hours after the mobile number change before accessing My T-Mobile with the new number. update the new number on any accounts where it's used for notification, like bank accounts, social media, account verification, and notifications. 8.Caller ID will be refreshed within 24-72 hours Would you like to confirm? Do you confirm?